What is body dysmorphic disorder?

Hi I have been "bulimiarexic" (no binging just restricting & purging) for over a year now. My parents don't know only my bestfriend Tara does. And my other bestfriend Lindsay knows too (she's a few years older than me). I'm 14. I read something on a pro recovery anorexia site about body dysmorphic disorder. Idk what it means but do you think I may have it too? God I hope not. Anyways I personally think my thighs are huge and for a long time people would not argue because it was the damn truth but now they're like "you are either joking or mental if you think they are big." But for real when I look in the mirror I see my huge hips and huge thighs and my obnoxiously large butt. But everyone says that I am not fat. People tell me I'm too skinny. But I think they are trying to make me feel better because how could I not see something other people can? Please help me. Do I have body dysmorphic disorder along with my ED? Because if I do then if I get it treated then maybe my ED will stop. God I hope it does, it is hell. Is there meds or intensive therapy that will help me with my awful self image? Thank you. This is ruining my life and I really want help.