Hi Shelly,
I can only speak to my experience with students that are at critical risk. Unless there is abuse, by law we can't assume the liability to providing living quarters to students who are under the age of 18. If a student is 18 and in a bad situation, we can get them placed at several support agencies in our community. However, I have observed that when a student doesn't have any family structure or boundaries, it is a challenge to get them to accept the rules and responsibilities that a stable environment has to offer. They want there freedom from a structured environment. We have found housing for students and many of them end up leaving because they don't like the expectations.
The Boarding schools that I am aware of are private faith-based schools. Maybe this would have been a good balance for you when you were younger. Opportunity to get away from painful issues, still having access to those in your family in which you felt supported, plus getting your education.
We are seeing a strong movement to address teen homelessness. We have to many hurting kids who have been abandoned and rejected. I hope you are doing well now and that you are in a safe and loving environment.