It's hard for me to separate how others may have perceived me vs my own subjective experience. Plus it was so long ago.
Over the years through side comments, I've gathered I was just perceived as super quiet and shy,and thus unapproachable. That, and sweet. And smart. Also, I was perceived as solely caring about academics, was voted 'friday night studier' senior year, and was honestly completely mortified by that, based on how ppl viewed me, and and internal anger re 'but I don't study on the weekends!' lolz. There was also some of the usual teasing that happens and is directed towards ppl with low confidence levels.
My internal experience was that I was totally scared of my peers, thus wasn't close to anyone, and I felt I was behind a glass wall, not a part of anything. I had a few friends, but I had a lot of social fears and thus didn't do much with ppl outside of school. I read at home, and went birding, and was into music/orchestra.
I've since realized how much of this was a self fulfilling prophecy, but it was what it was.