First of all, *GREAT BIG BEAR HUG*
From what I understand (and correct me if I'm wrong), some people cut and starve themselves because it is something they can control. This seems to be the case with you, yes? Is it possible to try to replace it with another action?
Sorry I'm a little out of my depth with this although I feel/have felt similar before. Do you have a therapist?
There's a quote I really like that I think might fit here.
"And finally, this question: the mystery of who's story it will be. Of who draws the curtain. Who is it that chooses our steps in the dance? Who drives us mad? Lashes us with whips and crowns us with victory when we survive the impossible? Who is it, that does all these things? Who honors those we love for the very life we live? Who sends monsters to kill us and at the same time sings that we will never die? Who teaches us what's real and how to laugh at lies? Who decides why we live and what we'll die to defend? Who chains us? And who holds the key that can set us free? It's You. You have all the weapons you need. Now Fight!"
When you win and know you can win, it's a powerful feeling. It's worth fighting for that power no matter how hard it gets. Don't take my word for it though. Find out for yourself.
(Sorry if this comes across as flippant. I am in no way meaning to make it sound easy. Just trying to be encouraging.)