We are in the middle of multiple transitions -- moving from Montessori to traditional, skipping a grade, deciding math placement. And of course we're looking at a few schools.
The conferences sound interesting. And now you've given me "permission" to go, I won't feel like such an impostor.

It would be eye opening to see dd with a group of kids more like her.
You are no impostor - more like almost a Standard Deviation above the usual definitions of gifted! I love Dottie's advice to go at SAT or ACT - and would do that this spring, and then apply to Davidson with what you have. The tests are much less kind to 11 year olds than to 7 year olds - much less headroom.
As for Math placement, can you get the books that are used in various Math classes (or old final exams?) and see if the previous teachers would help give you an idea of where they think things might work best?
Lots of changes - good luck!
Grinity