Therapy for dissociative disorders has come a long way. Trauma therapists are getting much better at supporting people who have had extensive trauma histories and have dissociative disorders, so it might be worth giving therapy another shot.
I have a good trauma therapist who uses internal family systems (IFS) to help me work with the different parts of my system... like we have a part that tries to not let anyone talk, and parts that want to talk, and parts that want to punish ones that try to talk and other parts that make us feel like nothing is real and it is all a lie etc. All of these different parts have important jobs that were all a part of trying to keep us safe... but their jobs just make life and therapy and trying to tell a bit confusing now.
Anyway, our therapist uses IFS to help us work with all of these different parts and find ways to talk with them and work together in a cooperative way.
We find it helpful (but it is hard work) and we are making progress slowly but surely. So maybe therapy with a trained trauma therapist might be worth another go for you?