Hugs. My kids are way younger but I can't imagine how difficult it must be to watch your child put road blocks up in front of herself. I don't think you're being codie (said one codie to another, haha) I think you're a rightfully concerned parent. I hope you guys mutually come a a decision that will benefit her best.
Side note: there was a parenting article I read years ago about a therapist who moved out of the family home at 16 after receiving her GED and started attending college classes. She was smart but so bored that she was acting out. Being on her own and more independent was the only way she could stay on track. Let me see if I can go find the article. The idea sounded terrifying to me, but maybe that's similar to your daughter's personality/attitude.