I agree with your T that the actual diagnosis doesn't matter so much, its more important to appropriately treat the problem-causing symptoms. A label just describes a set of symptoms and there isn't a massive deal of difference in treating the degrees of symptoms between trauma disorders.
I was diagnosed with DID last year but my T left her practise shortly after. Now I see a trauma therapist who is a EMDR specialist, I have been seeing her for about 9 months I think. We are working towards doing EMDR but haven't started yet. Last week we used eye movements for the first time to process some work with some parts but T said we won't start proper trauma processing for a while. She said we have to work on system mapping and developing more communication and cooperation between the parts first.
We still switch a lot in sessions and don't remember much from one session to the next, T said we need to improve that. Since using eye movements last week I can rememeber the whole session for the first time so that's hopeful.
My T has mentioned "mapping" but it seems we are just asking about the different alters, finding out things about them like how old they are, what their job is, who they talk to inside, what triggers them out etc. We aren't actually drawing a map of them or anything!