Lip picking & AutoCannibalism

Im 24 and only a year ago I realized my picking was an issue, and it was brought up to me by someone close. They thought I was trying to hurt myself, (previous history of self harm), but I'm not Trying to hurt myself even though that's Always how it ends up, I usually don't stop until I'm bleeding too much or it hurts too much. It started as a child for me, but it Was with my toes and fingers, I would peel my nails and the skin from the bottom of my nails all the way down to the next knuckle, until the Dr told me at the age of 5 that they'd have to amputate if I continued, so I started on the inside of my mouth, but I don't remember consciously making an effort to change that. But I've always eaten the skin and nails. Which I didn't realize was weird until someone asked what I did with all the skin I'd pull, I answered, and the reaction I got was pure disgust. They'd always ask me if I was hungry? But that had Nothing to do with it. I'm realizing more and more that people ARE seeing me do this, and it's making me more self conscious. How do you curb your compulsion when it's in your mouth???? And why is there the compulsion to eat the skin???