I went back and reread, and I think I'm starting to get the picture: Which classes is she subject accelerated in? How are things going in those classes? Does she have to work hard not to be the top student in those classes? What percentage of her day is with agemates?
For kids in the YSP program, a common accomidation that works for a while is a full grade skip plus more subject accelerations, so if that's what she seems to be needing - you aren't crazy!
so sad that she gets anxious when she is underplaced, but totally predictable. Makes it scary to do new and untried things onces she is already anxious from being underplaced in the first place.
I think in this situation, I would investigate what is going on in the subject acceleration classrooms. If she isn't getting exciting learning there, she might prefer to read a book in her agemate classroom. But, even if it is her preference, it doesn't seem to be working for her!
Love and more Love,
Grinity