I'm sorry you are struggling. Although I don't have DID I understand you dilemma with going IP. IP is really mostly a holding place and pill mill until those feeling at least appear to have passed. By now I think most IP workers know that "frequent fliers" know how to fake betterment when they are tired of IP. One idea, can you talk about the underlying issues with your T without it becoming a flag for safety. Obviously this is only if you are able to be safe. I have backed away from therapy for the most part and totally from psychiatry. Lucky for me though my T would not force IP(she knows I would not come back if she did) unless she felt absolutely convinced I could not be safe otherwise and I am now able to convince T that i am ok even when it is questionable(normally just means agreeing to go to ER if it becomes unmanageable).

Hope you are able to find that middle of the road and maybe stay out of IP if that is what you want.