well, as I hear from your story it might well be that you have an ED. But as I have experienced myself, you will not gain so much weight if you're eating better. I don't know if you ever read something about metabolism? That is the way your body processes food. And the fact is that it's working much faster if you eat more, wich means you could even loose weight by eating better. It's healthier, but still not good.
I think you should realize that, when you excercise this much, it's normal to eat good. Gaining weight when your underweight isn't bad, it's just healthier for your body. First you should realize that before you can get better.
I'm going through this myself too, so contact me if you need any support :)
greetz
Sometimes I do have body image problems, but doesn't every teenager have some sort of body image problem sometime in their life???
Personally, I don't think I have an eating disorder.
first question is, do you have a body image problem? do you think you have an eating disorder?