Hi Imomo66,
Is it normal? No, definitely not. Is it common? Yes, unfortunately. Is it something to be concerned about? Yes!
Every behavior has a purpose, meets a need, is a comfort in some way. You've developed a "skill" to manage something else in your world that seems unmanagable. Maybe the stress of school, someone commented on your appearance, suffering some sort of abuse or trauma. It's easy to say, "Oh, I just wanted to lose weight and be thin." But there's something driving your need to lose weight to an extreme. THAT is where you start soul searching. Consider that there are so many healthy ways to lose weight, yet for some real reason, you chose one of the hardest, most dangerous ways. Why?
Also, be aware that eating disorders are VERY addictive. Your body will crave purging after you eat even if you don't want to. (I speak from experience.) It throws all of your body chemistry out of whack. It thinks your starving so it wants to gather up all of the calories it can. Hence craving sugary, carb heavy, and salty foods. The "good for you" foods just don't have the punch to your system like junk food.
You're probably dehydrated. If you continue to purge, make sure to replace the fluids you lose. Preferrably something with electrolytes, like Gatoraid. Also, add a B complex vitamin to your day. You'll feel much, much better if you can. Eat potassium rich foods bc your probably running on empty. Potassium is the stuff of life. Don't take it lightly.
If you still have control over whether/when you purge, STOP IT. If for the sole reason is saving your teeth. That's no myth. When you purge, your digestive juices attach to whatever organic thing they can. That's what they're designed to do. And they will try to digest your teeth! I've had two teeth pulled and have a least one filling in every tooth, some have two fillings. One of my teeth has a crack caused no doubt by weakening enamel. I can barely stand to chew on that side, now. My dental care is off the charts financially stupid. A filling costs $125, to get a tooth pulled $300. Eventually I'll need a partial, and I know those are up around the $1000 mark. And this is with having my teeth cleaned twice yearly (which cost $85.) Everytime I sit in that chair, I just wait for that pointy tool they use to check for holes to "stick." That spells another filling.
Oh, you probaly already know this, but cavities hurt. There will be a day you'll wake up with your face throbbing. Also, you're teeth will get super sensitive; hot and cold things feel like daggers to your teeth.
Jurrian (Jurplesman) might have some useful advice. Hopefully he'll chime in.