Since it's a private school where you're already paying tuition, this might not be a good idea (after all, you're paying the school to teach her)...but could you partially homeschool or afterschool? If she's already quite advanced in reading and math with presumably no instruction, she could do different math during class math time and then maybe you could teach her English, and then she could take science, social studies, art, etc with agemates. This might not be possible with scheduling conflicts, or it might not be right for you, but it's an option. It might create issues academically later on, but you could try to slow the pace with enrichment, etc - and at some point issues might be inevitable.
