I've been seeing some very slow results, and am starting to feel really frustrated.
I'm going to put on my "mean Phoebe" hat for a moment, but I don't mean it personally. You are *not* seeing slow results. You have unrealistic expectations, and you are confusing water weight fluctuation with fat loss.
For example, on 11/13, you posted you were 145. Then on 11/14, you were 139, and on 11/16, 137. That's water weight loss, and it'll come back just as fast as it left, for reasons that have *nothing* to do with fat loss or gain - like eating a salty snack before bed or girly hormonal issues.
You're already "normal" weight by BMI, and so your goal ought to be very slow loss, in order to preserve your lean muscle mass. So one week in, you shouldn't be down more than a half pound IMHO - and that level of change just isn't visible on the scale in the short term, because of water weight fluctuations.
when I've looked in the mirror, I just think I'm ugly and I hate my body. I even started to cry the other day. What do I do?
Throw a towel over the mirror, so you don't look in it. I'd guess you're going to get your period in the next week or so, which would account both for water retention and general misery, at least for me. (I also notice a recurring pattern where exercising at a level I'm used to is much harder the week before my period - I just feel weak, if that makes sense.) Wait it out; this too shall pass.
I want to be really fit and toned.
What about putting the weight loss goal on hold for a while, and working on strength training? Girls don't have the right hormones to get big bulgy muscles, so don't worry about that. But some muscle development will make your body look less flabby, even at the same weight.