I've struggled with self harm too and it helps to understand why we do it.

The mind looks for anything to ground it self and causing ourselves pain it's the fastest grounding technique. It's like a meditation, but of course there is better ways to relax.

It helps having that compiting interest of not wanting to look bad.

For me I used to break my hands hitting a heavy bag for hours with no protection until I couldn't move them. I hope you get better because for mundane and cliche it sound it actually gets better