Yes, that's it! The phobia. I couldn't find the words to say it, but I really think she may have a phobia with it. It's like because she has empathized with me in the past, she may have to admit to x, y and z about herself. Sadly, it is causing issues.
She wrote back another long email about how she understands the process of dissociation, she just wants to "make sure" that my dr is not putting false memories or ideas in my head. And I go out of my way to NOT prove myself to other people. If she wants to believe me, what I've already told her will be enough. If she doesn't want to, nothing will ever be enough.
What I would like to say is that she either accept me as I am (ie where I am and what I identify with), or at least stop bringing that up all the time, or we go our merry ways. She keeps hinting that unless I know for sure I was 'definitely' abused, I cannot say I have been traumatized. (this is another sensitive spot with her, the proof of abuse).
I just wish I could think of something nice, yet firm to explain to her that her negative opinions are putting holes in my relationship with her, without blaming, sounding unkind, or offending her.

Anyways, thanks for the input

As far as people thinking we're making up the mental illness, it makes me sad. I wish people could just admit that they don't know everything about other people, and accept people where they are, instead of where they think the person 'should' be.