Yea agree with Threemothership. Im tall and so is hubby so my daughter foot is big compare to some kids..it just varies.
There is no normal unfortunately, you can get sneaky is she on fb and does she post pictures of kids with other kids and tag parents... If she does and similar age you could contact her friend and ask... Good luck!
My son is 2 and half and wears a 9... But I thinknhis feet are bigger then average