My sister has bulimia, so I know this is tough on you. The main thing is that you realize yourself that you have a problem. One thing that would probably make yourself feel a whole lot better is taking up a sport if you don't already do any.
I'm really sorry to hear you feel so down about your shape, but honestly, in one form or another, it happens to most people. As a general rule, most people have at least one thing they'd like to change about themselves, and you're probably no different.
Try doing things to make yourself feel more feminine. It sounds such a cliche, I know, but even if you buy yourself a small piece of jewellry you really like, or a pretty top, anything that boosts your happiness and makes you feel more ''girly''.
It sounds like a lot of this is purely in your head though, since everyone else tells you you look great. If you were to post a picture up of yourself here, no-one would see what you see. This is all purely mental.
Hang in there, and hope you start feeling more confident.