Hey there!
Incredibly relatable, but that's not going to help you. In my experience, a certain level of healthy eating (or self care in general) needs to be maintained in order to work on the underlying issues. However, as you mentioned, it's difficult to do so. For instance, going through trauma treatment requires you to be able to deal with whatever comes up in a healthy way, not coping with it through binging or purging. But reliving those traumas, triggers all the disordered behaviour to come out.
What helped me was setting goals i could keep. For instance, setting a minimum weight, a max of x behaviour per day/week/month/whatever fits your situation. Because i was motivated to work on the other problems i was having, this closed a back door. I didn't expect myself to not have eating disordered behaviour, as it was absolutely impossible (and also rather unfair) to demand that from myself. But it did keep me on track and focused on what i wanted to deal with.

I hope this makes any sense - probably not. Oh and please keep in mind I'm obviously not a professional, the only thing I'm professional at is making a mess of my life .
Lots of love and good luck, i truly hope you find a way that works for you