I was forced by my parents to go to a small (religious) private school, K-12, in which there were 5 kids in my graduating class, all of whom lived very far from each other. Your analysis of things just feeling "askew" perfectly describes my time there. I still have nightmares, over 10 years later.

Other people who graduated from there (i.e. family), think it was just fine, and think i'm just being dramatic about it. I try to explain why I hated it so much, but it seems like no one cares or understands. "It's school, you're supposed to hate it," etc. But perhaps the religious aspect, in combination with the feeling on isolation from other people your age, just didn't sit right with me. Most people can eat peanut butter and be just fine but some people are allergic to peanut butter. This school was my peanut butter.

My little sister is graduating from there this weekend and I tried to get out of attending the graduation ceremony, but she guilt-tripped me hardcore into going (to the point of yelling and crying). I haven't been there in 10 years and I am dreading it, churning up all those bad feelings and memories. But I know if I don't go, she will hate me for it. Christ, I fucking hate that place.