why do i eat my scabs?

I have been picking at my scabs and biting my fingernails/cuticles for as long as I can remember. I have always ate my fingernails and the skin around them, now i eat the scabs i pick too. Where ever i can find something to pick on my body, i will eat it. I will pick at anyone that will let me; their scabs, pimples, nails, dead skin, etc. But i have recently started eating my boyfriend's too. I only eat his and mine.... it's still gross, but i can't stop! I used to hide the eating part from him but now he knows that i do it. He is grossed out by it too, but we both know it's obviously a problem so he's not mean to me about it. Everyone that knows me knows i pick, but i hide the eating part from everyone but my boyfriend because it's embarrassing and disgusting. However that is not enough to make me stop. I constantly have visible sores all over me and plenty of scars from it too. My nails are also embarassing and so not pretty. I want to stop picking/ eating to stop the damage and scarring..... but i don't really want to stop picking/ eating because i like doing it. It's almost satisfying in a way. I have been diagnosed with anxiety, OCD and depression, but again i feel this is a seperate issue. Do you have any advice answers or anything that could help me?