Hmm. The first thing I notice is that there is quite a substantial difference between her Verbal and Perceptual Reasoning index scores (and BTW, is the PRI using extended norms, or no?). A nearly 2 SD difference between the indices suggests a skewed learning profile, which potentially could signal a 2e. That, and the middling PSI (although one should always consider that Avg/High Avg PSI is not that unusual in gifted kids).
I bring this up in particular because Everyday Math is a highly verbal, writing heavy math curriculum, with an emphasis on "process" which plays rather to the disadvantage of naturally mathy kids, who honestly see no process between the question and the answer. It's one of the classic constructivist, Chicago Math-style curricula developed by verbally-strong educators. A lot of time (even when you do receive instruction) is spent on exploring and "discovering" math principles. She is strong, but not stratospheric, in language, but is being asked to restrict her progress in her area of strength to the level of her relative weakness. Without support for the weakness. (VCI of 124 is kind of borderline for a one-year grade advancement in writing, which is what has, functionally, been done here.)
As to the shyness, all of the factors you have named are possibilities. I would add that G&T programs also tend to be biased toward highly-verbal, extroverted children, as that is who teachers preferentially nominate. So now she is also in a setting that is full of these chattery, socially-assertive peers, which might make a shy or introverted visual/nonverbal learner feel just a bit overwhelmed. She probably needs a break at lunch, after struggling with the constant verbal bombardment during class.
I would suggest building her social skills by selecting quieter, less-emotionally and -verbally demanding peers for one-on-one play dates. In the school setting, she may need the quiet time. I wouldn't demand that she have to play or converse with groups of children all the time. If it is necessary to work in a group, build in restful alone time, so she can balance solo refreshment with group exertion. There is nothing wrong with being a person who is energized by being alone and reflective, as long as you gradually learn to manage being with other people, and engage in a few selected deep personal relationships.
