If she doesn't believe that DID is real, I would seriously look into finding someone new. I spent months seeing a dr who was positive that I could not say I'd been abused because I was only starting to remember things this past year. If there was physical proof, he'd have believed me, but he didn't believe a person could supress memories and suddenly remember them. Absolute rubbish. I was able to finally see someone else, and the new doctor has really helped.

Does your t explain in a reasonable way why she thinks it's different? or have a diagnosis that may fit? There would be a difference if she was thinking that some other name/diagnosis fit better than DID, but if she doesn't believe in the ability for a person to create alters, this sounds like it could be damaging to many aspects of your relationship with her. How can you work with and trust someone who doesn't believe you? And even if she didn't personally believe it, she should be meeting you where you are (in this case that DID is your daily reality) instead of forcing you to adopt her opinions.

Good luck with it, and keep us posted on how it goes!
xoxo
IJ