Cassy, I see you're in the UK - I know from my own experience that therapists in the UK aren't trained or qualified to give a formal diagnosis. That needs to come from a GP, psychiatrist or clinical psychologist. Your T may well be able to see the signs of PTSD or DID but can't give you a diagnosis - if it's really important to you, would your GP not be able to help or is that you want it not on your medical records?