Feel like im losing who i am?

Right now i am 18 years old and im very confused about what is going on with me. 2 years ago i started smoking pot like 2 times a week for the summer. i went on a family trip and wasn't able to smoke. then i got back and smoked a bowl of some high level stuff and got completely freaked out. it was the worst high ever. i had my first day of school the next day and felt like i wasn't myself. i couldn't have good conversations with people and my confidence was way down. i became very anti social for most of the school year, and i was off the pot for good, nothing changed though. then i regained my confidence by doing speeches in speech, which i could not do in front of an audience, i only did them in front of my teacher and principal. i also started to work out, and then right before the summer started i felt like a whole new person and i was on top of the world. i tried chugging some dayquil in the middle of the next summer, but i was able to get over that, and i never did it again. then my senior year started and things went down slowly again, its like school put a course on me. it got even worse, i started to get effected by thoughts of "Where does life come from?" "are we just a bunch of developed apes?". i really started to question my religion and i started getting panic attacks. its kind of embarring, but i also started masturbating alot and im sort of convinced god is punishing me with the anxiety and anti socialness. im now on .25mg of alprazolam and 12.5mg of of zoloft. i also exercise alot now too and don't jerk off. can anybody give me some advice on how to get my life back?