Dealing with Isolation in Senior Year

how do you deal with isolation? i’m going into my senior year alone (no friends, can’t seem to keep any). dealing with all my issues on my own it’s hard enough, but now i’m doing worse physically and mentally with the stress of school, and now there’s this lack of social life too. i don’t know what i’m doing wrong. i check in on friends, try to make plans, i’m always there for them but it never seems to matter. it’s so hard feeling so alone.