Hi K,
How much do you eat or sniff at a time? How often per day?
I suspect you are not going to the doctor because you know darn well he is going to tell you to stop and deep down you don't want to. You better go or YOU WILL kill yourself. If you stay on the same path you will die, I have no doubt about it.
I know when you are young you feel so invincible but something like comet cleanser will wipe you out. Please oh Please get some help. Your doctor is there to help you and not judge you. Let him/her do their job and give you what you need to stop this behavior. Please have full check up including blood work and face up to some damage you may have caused your body so you can be put on a healthy path.
I am also sure you want to have kids one day also. Honey what you are doing is slow suicide whether you want to admit it or not. Think about how many people will be absolutely crushed if something ever happened to you? If you don't stop for yourself, please stop for your future children and all those that love you.
Believe it or not I am now crying myself while I am writing this. I feel like I wish I can come and sprinkle fairy dust on you and fix you right up. I wish I could write something like "sorry I am scaring you" but... you should be scared right now, real scared.