I think I'm anorexic, but?

I think that this is something you need to watch. If your fainting etc , then your obviously not getting enough calorie intake. You need to go and see a doctor, you cant just wait until you fall in the "underweight" category until you do something about it. Its good that you realise that there's something wrong. That's the first step to recovery. Don't listen to your mum, shes obviously in denial about the whole thing. Your doctor will be able to refer you to a specialist so you can talk about the issues your having. Your mum doesn't have to know. I would personally tell a close friend that you trust, just for support, as you will need it. You need to change the way you think about food and the way you feel about yourself. That's very difficult when your in that situation. Im currently recovering for bulimia and telling a doctor was the best thing i could have possibly done. You don't have to be underweight to be ill. Why don't you print this question off and take it to your doctor to read, its sometimes easier than actually telling them what the problem is. The fact that your not having periods, worries me, you need to get that sorted as in the future you may want to start a family. Its all about building your self esteem back up, once you have achieved this, the whole weight thing will sort its self out. Hope this helps!