I just happened to find this site now and there are probably other people with more experience than me here, but I feel it's terrible since your so young, you have to get better help. Try to find someone to talk to first of all, do they have someone at your school who can help you out maybe, or a psychiatrist, just talking to someone is always better than talking to yourself.
Then try to find a group in your neighbourhood for bulimic or anorexic. I thought I was too fat too when I was your age and thought the bulimia groups wouldn't believe I could have bulimia since I was sooooo fat(my opinion). You most likely think you are too fat because you are sick right now!!! You can't see it and it can take many years to overcome the wrong picture of yourself and it probably doesn't help that I'm writing it down at this moment. Anyways, I think one part of the problem is the food you are eating is not good enough for you or something might eat you food such a parasites so you can't get enough nutrition. NUTRITION is one of the keys for overcoming bulimia I think, but I never had anorexia although I starved myself so I'm not sure of that problem. Try to find some good parasite cleanse and do that just to be sure that your body is clean. It might be a really stupid suggestion but most people have parasites in them without knowing it, and they steal nutrition if they are in the intestines. It doesn't have to be expensive. Since your mother knows you have bulimia she's most likely very worried. Ask her if she can pay for it, since you are worried you don't get right nutrition. Also if you dare, try to eat both fats, carbs, proteins, and vitamins/minerals/fiber You won't get fat if you eat flaxseed oil for example, because it's a fat that the body truly needs. If you eat vegetables with lunch and dinner and flaxseed oil you won't get the cravings for too much carbs and you will get better cognition since the brain uses fat and glucose for operating. There are as many opinions on food as there are people but the idea that fat should be eliminated is stupid. Anyways when your don't have parasites and get better nutrition your body will have a chance to recover and give you the right signals. The key for getting rid of the body's fat deposits is right amount of nutritios food and some exercise. If you would eat like that you might not like the results, because most people look normal that eat like that and you might want to be a lot skinnier.
You probably also exercise like crazy or you might not exercise at all if you too tired from starvation. After you get some nutrition in your body you will get higher serotonin leves just by being out walking or biking for a while. You don't need to exercise for two hours. The best combination for getting rid of fat is walking long walks, sometimes you can combine it with harder exercise 2-3 times a week if you think it's fun to do.
The other part is your relationships and feeling of self worth. I don't know anything about you but chances are you are not very happy at home or at school. If that's the case, talk to the family member who you have problem with if you can do that and tell them that exactely how you feel in whatever circumstance you might be in. Tell them they can't say a word until you are finished. If you happen to have problems at school it's a little bit more difficult and it's hard to say anything on that since you didn't give any information.
When you are about to binge eat, try to think how youre feeling right now. It doesn't always come right away. You might be very angry or sad or both. Let's say you are very angry, wouldn't it be nice if you could start kickboxing or do something else that could reliev anger. Also you can try to be angry at the ones you are angry at. Also right before you will binge eat, try to sit down for a moment and think if you can just hold on 5 minutes the worst feelings might fade away. Try to make it a habit since habit is the thing that got you hooked on bulimia in the first place. Although you won't succed the first times, try to think if you can wait a couple of more hours to binge eat then you might not have to when the time comes.
I think one part of why it's so hard to stop binge eating is it's an addiction, due to hormones. First your are very nervous/irritaded/angry or whatever and start to eat and the relaxing hormones are starting to work. Then you feel terrible and fat and start throwing up and afterwards the relaxing hormones are starting to work again, instead of stressing hormones like adrenalin/noradrenalin.
You probably already know that when you don't eat the metabolism slows down. When you start to eat again after starvation and eat "normal" unhealthy, non nutritious food the body will store more fat. The key is to eat a couple of times a day 3-4 and also the bloodsugar will stay normal that way and it will also take away desire to binge eat.
To make sure you get enough vitamins and minerals, buy colloidal extra minerals/vitamins in a helth food store and also flaxseed oil since it has large amounts of both omega-3, 6 and 9 that your body can't produce by itself. If you want to be super healthy you can also buy vitamin-c extra but it's not necessery . Look up Linus pauling nobel prize winner on vitamin-c. Again, tell you mom you are worried you will get worse if you don't. Your thinking process will get a lot better by doing these things, even when you starve yourself you will at least get some nutrition in you body.
Hope you might get some help from that and remember it's only my experiences, I haven't talked to anyone about it or researched anything on bulimia/anorexia. Even when your'e better you will get relapses but don't get discureged by that. The relapses is often becuse you are so used to follow the same pattern in your life (if youre not starving yourself,or eating non nutritious food, then it's probably because of that).
Try to develop some interests, whatever music, poetry, sports and when you have fun and getter better at different things you will be more self confident and will se yourself in a different light. Don't sit at home thinking about sad things. It doesn't lead you anywhere.