Oh honey, I'm new to this forum and sorry I didn't see this post back in January when you posted it. It's August now, and I hope you're okay. I remember those same feelings when I was 15... (I'm 44 now and doing fine - hope this offers some hope for the future).
Parents have ways of really making a kid feel like crap, I know. They don't know they're doing this. To put it into perspective, they're people with their own screwed up ways of handling or responding to stuff. The damage they inflict (no, I'm not talking about beatings and such) are usually NOT intentional, really, and they're probably doing the best they can (given their own dysfunctions and how they might've been raised). You're in the middle of one seriously challenging phase of life. No offense, but the hormones are probably "akimbo" right now too, and that doesn't help when mixed with the self esteem issues that your parents may be inflicting. These rapid changes of maturing can definitely cause a heightened sensitivity... and it's not a bad thing, but how you respond can be, and it seems this is the case with the self destructive actions you are taking.
This is difficult to recommend in the midst of your years now, but I wish that I had known how to perceive this when I was 15. Ok, My parents are wacky... they're hard to please and apparently wrapped up in their own disappointments and shortcomings in their own lives. This is cuz of their upbringing too... One day I finally saw them as "people I live with who call themselves in charge of me" and they "had issues"... and I had to forgive them and make a pointed effort to live my own life and stop the negative stuff resonating down from generation to generation. It helped to view it this way instead of seeing them as just "my parents". I still tolerate them to this day!! but I love them... I have no other mother and father, and I don't allow them to affect my self esteem so much anymore. (even though they still try on occasions!)
This forgiveness, and trying to not allow their issues to become your issues is hard to do at your age... Why? Because you're developing into your own person, naturally, and yet you're still under their thumb (you kinda HAVE to be at your age). Can you find creative ways to express yourself and frustrations rather than cutting and vomiting? Can you do some gnarly painting or find an art form of some kind to get these things out and help you cope until it's time to be old enough to leave the nest and really be your own person? A martial art is a super excellent way to change what you're going through as well. Ever thought about kick boxing, Tae Kwon Do? You'd be a rockin chick with growing inner confidence that would be immune to anybody elses whim or response! Can you consider these things?
I hope you respond to this post soon. Even strangers can care a lot about you and your well being.
Keep these things in mind?
Balance is a harmony, not an extreme.
and
It's not what happens to you that matters, it's how YOU RESPOND that matters.