She did pick them out, and tried them on. We had measured her before we went shopping and so we pretty knew much what size to look for. The bras she has fit. She just says they're too uncomfortable. She doesn't like anything even slightly tight around her body. She pushes her underwear and pants down below her belly because she doesn't want them pressing against her tummy.
Oh well I guess eventually somebody at school or wherever will make a comment to her and maybe that will help her realize she needs to wear it no matter if it's comfortable or not.
Thanks for the thoughts!