As long as your daughter is having anxiety issues, I'd forgo boarding school. She would be without her safety net (you and DH). Right now, you're there to help her deal with the problem. Talk to her about it, ask her to try to define what starts an "episode". Let her know that you need to figure it out before you're willing to send her off on her own. It does sound like SI could be the culprit, but i've only dealt with it in babies/toddlers.

Shari
Mom to DS 10, DS 11, DS 13
Ability doesn't make us, Choices do!