Another thing that worries me is that between the 2 first grade classes 7 kids will be going to the 2nd/3rd G&T class next year from our school. The G&T program is district wide and our school houses it for our city. So it's not just for G&T students in our school. So the fact that she is already struggling to fit in with such a high number of G&T students already in her class.
Not to sound totally jaded here

, but if your GT identification process looks anything like it does where I live, I'd say that the reason your dd isn't fitting in with the other GT kids in her class already is that she is either a lot more gifted than they are or they aren't actually gifted in the way I consider gifted to be defined: high IQ and different brain wiring not high achievement, group test scores, convergent thinking, and teacher pleasing. The input we've gotten over the years from gifted coordinators, teachers, and district personnel who actually got what gifted is has been: dd is one of the most gifted kids they've ever taught, most of the kids they have in GT with GT ids are not actually gifted but rather high achievers, that we should consider homeschooling b/c they don't have anything in place to meet the needs of HG+ kids, and a variety of other things along those lines.
Your post wasn't rambling at all. You are describing a child who sounds like a hybrid of my two dds so I really feel for you here. The one year that worked well for my older dd before she was given the chance to accelerate significantly was 2nd grade. I approached it without stressing dd's giftedness to her teacher although I was just starting to realize that this was the problem. I focused on the types of things you mentioned when talking to her teacher about her needs: slower processing, introversion, desire to really learn in depth, her areas of passion, etc. It very much helped that the teacher herself was quite intelligent.