@LittlePickleHead Hi - sorry to hear about the self harm. As others have said, I've shared our approach to managing self harm.
DD's had a variety of CAMHS workers - some focused on the ED and some focused on the anxiety and self harm. The latter group worked with her on a "keep me safe" plan.
The plan described how she felt, and behaved at different traffic lights of green, amber, red. It also set out what she could do to de-escalate and what she needed us to do.
DD have certain physical 'ticks' that we knew meant anxiety was escalating - she would scrunch up her shoulders in a particular way and have her hands near her collar bone - this was a sign of her moving to amber. The move from amber to red take place in a nano second so we had to try to de-escalate promptly at amber as once she hit red it was a long time of self harming.
As she moved from green to amber we'd do grounding things like "Name five things you can see that are blue, name four things you can see that are yellow etc" It would try to create something new in her brain to focus in on.
DD route to harm would often be initially scratching/gouging on skin, hitting herself and then on to head banging off walls. So our amber activity tried to give her hands something to do - she'd use a tangle toy to give her fingers something to concentrate on, or we'd throw a bean bag or toy around. If things still escalated we would then get ice cubes and she'd hold them in her hands for the longest time.
Because we knew her hands were an important part of her trigger process, even at green we'd try to do distraction exercises that kept her hands busy so playing bananagram, we took up macrame, she made jewellery.
The keep me safe plan also detailed when she was wanting us to physically touch her and when not.
Obviously, we had support in writing it but as a starting point I'd think about what you notice when she's moving from her version of green to amber to red - what do you notice about the way she's holding her body, or does her tonal speech pattern change, are 'hands' an issue for her etc. See if you can draw out a sense of how she's passing along that spectrum and think about what could help as distraction - the plan should be led by your DD but it is helpful for you to do some observation and thinking in advance.
As ever, good luck and this won't always be as intensive and disturbing - recovery will come