Self-harm during meltdowns (obvious TW: self-harm - inc. brief mention of some methods)

So this is a bit of a delicate one, obviously, but I just wondered whether anyone else here was a self-harmer, and how it related to their autism, emotional dysregulation and meltdowns. I've been a self-harmer since I was 14, which is now 20 years - mostly by cutting, but occasionally other things as well such as overdoses or burning. During a meltdown, I will also head-bang, wrist-bang, scratch and hit myself and pull my hair out. 

I guess I'm just wondering how other people manage their self-harm and whether people had found things which were actually decent alternatives which work for them, or ways to avoid getting to that point. I've heard and tried a lot over the years (e.g. drawing on yourself with pen, holding ice cubes, flicking elastic bands, hitting something else like a pillow), but none of them work. I feel like perhaps those are geared towards people who aren't in an exceedingly uncontrolled emotional state/meltdown and once it gets to that point nothing else helps. I'm also in therapy and have been in and out of it for most of my life now - she's great but I always seem to fall into the same patterns because they're so ingrained at this point. 

I suppose I also just want to feel less alone with it. I've known a lot of self-harmers over the years, but none of it has quite been in the same context when it comes to the autistic meltdowns. I'm not sure what I really need from this, I guess, but hopefully some replies might be helpful or at least supportive!