You have already done the first step you need to do in order to recover: admitting that you have a problem. So you're already on the road to recovery.
Stopping an eating disorder is extremely difficult, especially when you have been struggling with one for as long as you have. Your body is now used to this routine and will reject any abrupt changes, so you definitely don't want to start forcing a regular diet upon yourself.
Unfortunately, there is no one method on how to stop an eating disorder. Treatment varies from the type of eating disorder and the individual experiencing it. The reason for this is that eating disorders begin due mainly to psychological factors.
The best way to end an eating disorder is to find professional help. Ask your doctor for a referral. Both a counselor and nutritionist would be best so they can develop a plan tailored specifically to your needs and recovery.
You need to develop a long term plan and stick with it even when you start feeling like it's not working. Most of all, though, you need to figure out what is triggering your disorder so that you can deal with those issues and avoid a relapse. Being comfortable with your body is important so don't occupy yourself with things that make you feel bad about yourself. Wear clothes you're comfortable in, don't look at fashion magazines, stay active, don't weigh yourself.
Also, try and find some support. Talk with friends or family and find someone you can talk to when you start feeling like resorting back to your destructive habits. Someone who will encourage you. Find a support group to join with people who are going through the same thing you are so you can encourage each other.
Many eating disorders develop out of self loathing, so if that's your case, try to identify what you are feeling when you starve yourself. Fat is not a feeling, so if you start thinking that you are overweight or unattractive, there is usually an underlying emotion to that. Stress? Depression? Loneliness? Identify the feeling and then find an alternative way to deal with that other than starving yourself. Maybe you could read a book, call someone, write in a journal, go see a movie, listen to music, take a walk. Just find some other way to get rid of the unpleasant feelings.
I hope that you overcome this eating disorder. It's a terrible thing to deal with. I know you can do it! If you ever want to talk, feel free to send me a message at any time.