Babe, I'm really sorry you're going through all this. From a mom's perspective (and not to defend your mom, just to give you a different point of view), your mother is probably scared out of her mind, and worried sick about you. She just doesn't know what else to do.
We have a 12 year old son who has appetite issues because of a medication he takes. He NEEDS this medicine (believe me, if he didn't, we'd yank him right off), but he has a hard time gaining weight, and he's not growing at as quick a rate as he/we'd like him to. Now, part of it is genetics. His dad is and always has been very skinny, but our son used to be the tallest of his friends, and he's now one of the shortest.
Believe me when I tell you, it upsets us as parents. He has ZERO appetite most of the day, but he has to eat to grow and be healthy. We have to basically beg, bribe, fuss, hover, threaten, etc all day every day to get him to eat. He FEELS full, but he's NOT, so if he forces himself, he can do it, but it's a struggle.
The doctor told him several months ago if he didn't gain three pounds in three months he would HAVE to take him off his meds. That scared him enough to get in gear for awhile, but he just got braces this week, so we've had another setback.
As a mom, I can tell you, it's very very difficult to watch your child suffer, and sometimes I think we react in ways that can make it worse.
Let me ask you this, if your doctors thought you had anorexia or bulimia, wouldn't they be suggesting you go into a treatment program? Maybe you could point that out to her.
I know everyone is different, and I don't know you or your mom, so obviously I don't know where she's coming from, just where *I* come from, but maybe this will be a perspective you haven't thought of.
Best of luck.