I'm a 17-year-old female (5'4"-5") and I weight 147lbs. I'm hoping to lose between 20 and 30 pounds in time for summer. At the end of October, I got myself one of those "mini stepper" machines, because I don't really have many other means of exercise where I live.
Congratulations on buying the mini stepper, and choosing a practical and reasonable goal for yourself, young lady!

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You DO NOT need magical devices to lose fat tissue. The mini stair stepper and body weight exercises along with proper diet, can and will get the job you are seeking done;
you will see the goal rainbow. In stead of a pot of goal at the end of the rainbow, it will have your shining and smiling face engraved in gold.
I have a maintenance line of about 2000+ calories or so, and I'm trying to keep my daily calore intake as 1,500.
MT Line=
2,000c
Calorie Deficit: -500c (1,500c intake)
How did you determine your MT Line of 2,000 calories? What formula did you use? What multiplyer did you use, etc.
The MT Line is supposed to be the calorie line that includes ALL ACTIVITES above your BMR (Base function calorie line), and this includes things such as work, training, etc.
When you say you "try to intake" 1,500c, what do you mean? So there is no misunderstanding on why I am asking this question, I will exapand a bit. When you are trying to intake 1,500c per day, are you tracking your calories and know for sure 1,500c is a VERY CLOSE approximation? Are you snacking or picking at foods you do not log within your calorie tracking? Small simple food items add up to 100c very quickly, and can take an additional hour to burn (example sitting at a pc desk burns approximately 120c per hour--dependent on the particulars of wgt, etc, of the person, and sleeping can burn 60 to 80 per hour). And, these little things can eat into the calories you burned in exercise and in turn makes your 1500c inaccurate, and thus your weight loss (or lack thereof) will show.
Every night, I do half an hour on the stepper, and according to its built-in calorie estimator, I burn about 250 calories per session. However, I have been doing this for about three months now, and not much has happened -- if anything, I feel much fatter. There have been days where I've skipped, or had a bit more to eat, but most of the time I'm reasonably good.
Approximate training expenditure: +/- 250c
Does this display allow you to input your age, wgt, hgt, and sex? If it does, this is more accurate than most, but I suspect still inaccurate (I dont trust them much). If it doesnt, than its even more inaccurate. Alot of calorie calculators on cardio machines, input averages, and not everyone is average.
NEVER EVER go 3 months again and allow no progress when seeking fat loss. Especially when one firsts starts out (assuming faithful to diet deficit), one should see tissue loss within 7 days with all things considered equal. ALWAYS critique fat loss at REGULAR intervals, and if fat loss ISNT occurring--something needs changing.
There are alot of things I do not know. At this time I know that you "skipped" or "had too much to eat"; however, I do not know the brevity of how much you had went over in calories or the amount of days (in 3 weeks) you skipped or ate too much. Dependent upon the aforementioned severity will depend how much of an impact it had on your goal. What I can say, I think quite safely, is that it did have an impact.
Lets consider things EQUAL for a moment: You determined your MT Line to be 2,000. You ate at 1,500c. You theoretically had a deficit of -500c per day. 5 times 7 is 3500 (there is approximately 3500 calories in one approximate pound of fat tissue). You should have lost about 1 pound per week IF YOU ATE STRICTLY AT 1500C per day--but YOU DIDNT. And your weight loss showed it.
If you are healthy, your calorie Vs. calorie expenditure is AMUCK--on one side or the other or both.
1. Tell me how you detemined your MT Line. Dependent on this information will depend on whether we need to adjust it.
2. Track your calories and what you eat PER DAY (some wont agree, but I am proof it can work)
3. Develop a program around your mini-stepper 3 to 4 times per week that INCLUDES a body weight exercise routine. Tony M (a mod) is a good one to give you examples.
If you track it. You have tools to change it; track it, change it and then battle it!
Its my opinion, that ALL bodily feed back IS GOOD, whether its positive feed back or negative feedback.
If its negative, than something is AMUCK, change something or you will more than likes get the same feedback.
(This happened to you)
If its positive, than you know something is right, but be watchful and careful of the degrees.
(We will try to get you here)
Same thing is APPLICABLE to the mind and mental attitude:
If its negative, than its going to destroying your goals, and something needs changing.
(Have something in place to battle your food cravings that inhibit your goal pathway)
If its positive, than you know something is right, and be keenly aware of its degrees as well.
seek knowledge to combat weakness and enhance strengths. One weakness you have right now, is that you allowed too much time to pass without changing something in your diet and routine. The body IS TELLING YOU that what you were doing wasnt the correct thing to do. Watch, look, and listen, to your body--it WILL tell you if you are doing the correct or incorrect things.
Being consciously aware of BOTH and having the ability to overcome them in the mind, is an essential successful element!
IF YOU WIN THE HIGHER PERCENTAGES of the battles in the head, you WILL overcome anything humanly possible.
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Some additional thoughts:
Item 1. It's not necessarily what you eat but a function of "how much of what you eat" that matters the most.
Item 2. In addition, its more of a operation of calories IN (energy-how much of what you eat) vs. calories OUT(energy-body function, movement and activities), that is the basics of lowering body fat or gaining tissue weight.
Items 1 and 2 are fundelmentally critical to your success in lowering your body fat/losing weight.
Go here and read on some basic and fundamental information:
Weight Training 101
Mreik-per-your-request-nutritional ]Mreik per your request, Nutritional sticky
Weight Training Technical Articles
How to get abs guide
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Item 3. Another essentional element in your weight loss/lowering body fat equation is "learning how to master the manipulation of calories (and macronutrients) vs. calories expended during various types of training/exercises."
This circumference of understanding will greatly assist item 4 (below). In addition, once you obtain a thorough understanding of your MT line, the deficits you are holding, and the amount of approximate calories expended during exercise, the variable tools available to you will give you a quality of vision few pursue to their personal goal advantage. Timing and application of this knowledge is a critical lever to have when problems develop--or even if you have a NEED to fill.
4. Additionally, its my opinion one needs to learn how to "master their self" within the confinement of the types of bodily feedback (psychological, biological, etc) that one WILL receive when deficit dieting or surplus dieting. It should be no surprise that if you deficit diet, that the body is going to kick in some psychological and biological defenses to compel you to eat. In addition, it should be no surprise that parts of ones personality (likes and dislikes, etc) can be a inhibitor. We can spend so much time on the basics on diet and fitness, and lose focus on one of the PRIMARY functions that can cause failure: Psychological and biological feed back of the body. Give TIME to gain knowledge on how to deal with them. Then learn how to apply what you have learned--you WILL NOT be sorry for the time or effort sacrificed.
Welcome to the forum. We do try to take the time to assist new and regular members. Sometimes its difficult because we dont know the level of knowledge of some that seek advice. I mean extremely well with this post. I wish you well in all that you do.
Ask as many questions as you deem necessary, and we will try to answer them.
Best regards and your friend,
Chillen