It is not anyone's 'destiny' to be bulimic. That is just a cop-out! You can change it if you want to badly enough. Your body is being weird because of the starving, binging & purgiing.
Get help & be willing to eat regularly (i know that's easy to say & hard to do, but that's the only way). If you follow a sensible meal plan you won't get fat & you'll get your life back.
I was severely bulimic & anorexic for more than 10 years & now I wish I hadn't waited so long to get over it. I kept telling myself that I would stop...Tomorrow, or next week, or at christmas. Well, that magic day never came.
This is a tough disease but there is hope. I've been in recovery for years now & I love my life. You can do it! Just stop making excuses & get help!!!