Hey Steff,
Remember that you don't have to post a new thread each time you reply. just go back to the thread you already started and "reply" to it, it will post under the last person who posted and create a running dialoge. Its a little confusing at the beginning
I get your reasons behind your weight loss motivation. That might surprise you because some other people here are NOT going to understand you and you may get some crap for it. I get it because I have been down the road you are embarking on and let me just tell you from someone who has travelled it far...its not as glamorous as you may think it is.
Bear with me as I use an illustration about what happens to someone searching for beauty and meaning in their appearance. Who feels more "worthy" when people notice them and feel they have to go to extra exremes to prove that worth.
It is a journey down a long long road:
You will get a ways down that road and at first it'll be great. The sun will be out, you'll feel happier than ever and people notice you making the compliments extra fuel to continue. After a while of this you will find that it will become darker and darker as you travel. You will realize that the "exit" signs begin to become less and less available and everything always looks the same. People may still notice you but some of their comments turn into concern and disgust. You may continue for a while thinking the end of the road is just "over the hill" or "around the corner" but you know Steph, there IS just NO end. None. It goes forever. There will be some point where you just stop in the middle of that road and look around the darkness. Not sure where to go or if you should stop. Afraid to go back, but too tired to keep moving forward. That will be a SUCKY day.
Your drive for thinness is in response to your cousin or to prove to your family you are valuable because you are "thin". First off, who defines beauty? Society has brainwashed females into thinking the only way to be acceptable is to look like Kate Moss or other ultra skinny models. You are depending on your environment to define your worth. what about YOU. What makes you confident about yourself? What do you do well?
Second of all, do you really think that once you get to the magical number your weight troubles will be over? no way. You may get to 90 pounds, but its totally unnatural for you to BE at 90 pounds and you will have to be more drastic than you already are to maintain your weight loss. You will have to dive to measures that promote massive destruction to your body for the long term. All in the name of weight loss. Try telling that to your future husband as you both long for children someday.
Third of all. The way you are eating right now is one of an anorexic. Have you ever in your life met a happy anorexic? I am willing to bet (and of course could be wrong) that if you eat you feel guilty. That exercise is your way of "cleaning" your system of the guilt and you rely on it to feel "ok".
This is at least how I operated, and by the way, my diet at that point was similar to yours.
This may all sound VERY harsh and maybe even mean. I do not mean for it to be mean at all. Harsh, well, yeah, because it is. My story in a nutshell: I weighed 84 pounds at 5'2, was hospitalized for 3 weeks, forced to eat massive amounts of food to gain weight, and went through tremendous HELL in the process of "getting better". It is NOT worth it and I vowed at that time (I was 14-15 too) that if I could ever prevent someone from traveling that road I would.
Think about what you are doing girl. Please consider healthy goals like toning your already thin body which will add sexy muscle, burn more calories and give you an even thinner appearance (even if the scale doesn't show it). I am around 130 pounds. You may have just gone

. lol. I'm now 5'6 and I'm a die hard athlete. I love the way my body feels when working out and I love a challenge. But I eat. I eat to fuel my exercise and my body responds with lower body fat, lean muscle and people who know me tell me I must not weigh over 115. I wear a 4 in most pants. Muscle does wonders.
Just think long and hard about what you're considering, its all I ask. If you ever want to chat, PM me. I'm always open to that.

Thanks for reading.
Take care~Katie