I am in the same situation as the OP (my kid is entering 1st grade this Fall). Throughout the K year, my gifted son went to the mixed class (1st/K) in his "top rated" school and they let him join 1st grade for Reading and math and it was not sufficient to meet his needs. He ended up being placed in a reading group ahead of all the 1st graders, so they put him and the teacher in a separate reading group (too lonely for my social boy), he goofed off during math instruction because he was bored and started distracting other kids at class.
My best suggestion is - afterschool (you say that you are exhausted meeting her needs, and that is why I am not suggesting homeschool).
I have rigorously afterschooled my DS with accelerated math, LA and science curriculum that challenges him and keeps his interest alive. There are a ton of options and curriculum available out there. You may even do it on weekends, vacations and holidays.
The only problem with afterschooling is that it interferes with extra curriculars and it comes at a time when the child has had a long day and is tired.
Good luck.
