Is this too much for a 12 year old?

Wow! That's a lot for a 12 year old. I think it's all right as long as she has some free time to do what she likes, and she's not overwhelmed at the end of the day. If it starts looking like it's way too much for her to handle, maybe she could do gymnastics or ballet every other day. She should get some form of a break every now and then.