That's not good for you, starving your body for a long amount of time, then shocking it with food, then purging. You're doing a lot of damage to your body.

Try to eat six small, low-ish cal meals. Distributed equally throughout the day and big enough to be nourishing but small enough not to have to purge them.

It's good you recognize that the behaviour is bad and needs changed. There are therapists that can help you. I'd suggest go seeing your doctor and get a referral to a T. If you're in high school see a school shrink, it's free. Chances are you're going to need help to change your behaviour.

Good luck.