Oh yes!
Not changing size or age, but changing places: yes, both she AND I.
It's indeed when she says something triggering. At the moment itself I kind of withdraw in myself, and I almost stop reacting. When I then think of the session afterwards, yes, we have changed positions. It's like I've been sitting on the floor, or in the extra chair at the wall, or by the window, and often she has changed places too. But mostly I moved. In reality we of course didn't move an inch. I once asked her if we had changed places. By her reaction I could see she was very surprises, and afterwards she told me that was when she first suspected I was DID. Now that I know more about it, it's indeed a kind of dissociating, I guess.

I'm by now quite sure that the place of which I afterwards think I moved to, is the place where I was staring at when dissociating. That seems to make sense. Somehow.

I never had the idea of her yelling at me or something like that.
But I'm also very much impacted afterwards, yes, by such a session.

Could you tell your T? I was also very reluctant about telling, and apart from her obvious surprise she didn't go into it, at that moment. She just reassured me we didn't move. She clearly had her thoughts about it then, but only later seemed to be sure enough to share those thoughts with me.