Just In Case by meg rosoff it's perfect if you want something with teenage vibes and only 170 pages!!

I would suggest Bridge to Terabithia. Though it is usually suggested for younger kids, I nearly sobbed when I read it back in 8th grade.

I like reading the O. Henry short stories, they are all just a few pages long and really fun! There’s another something a bit more modern floating around in my head, but can’t remember what, so I’ll come back when I do))

The outsiders. it's like 50 pages too