It's not psychosis, lobster, most likely anyway. I know what you're talking about. I self-harmed for years, and even when I stopped at 20, I still thought of it probably at least once a day. Even when all was well, it would just pop into my head. I dispelled the thought quickly but now, at 27 ( and with a relapse into self harm this last year), I can't imagine I'll ever be without the thoughts. No matter what. It's just part if me. I imagine it's what an addict feels even years, decades into recovery.

Try not to let it get you down. As bp nurse said, they're just thoughts.