I am in my mid 20s and went to a LOT of parties since i’m 18, ,,only’’ drinking alcohol and then with 21,22 stimulants like speed or cocaine was involved. Only at the weekends but when i was drunk and i saw someone with drugs i rarely said no. At first everything was fine, like normal hangovers and 2,3 days feeling down and anxious. When i was at parties i often consumed drugs that im not sure what was in it, like sniffing cocaine for example but it could be everything. I also took ecstacy but always the half and not so often. Then i got my first depersonalisation episode and noticed social anxiety everyday (one of the worst times of my life) it got better a little bit but i am not the same person anymore. There are days where i am really social and not anxious but something changed (maybe forever) it drives me crazy now im wiser and older and i dont know how much damage i did with consuming stuff and never know 100% what it was. 
I checked my brain with MR and everything seems fine on the organic but i am traumatized for sure because i have only few memories of the countless party nights with alcohol and drugs. 
I had fights, got robbed and was really a different person, sure the booze gives you confidence, but it damaged my soul so much, i was so young and dumb.
What could help me to get back to my old self, for the moment i have diazepam when it gets unbearable and i tried wellbutrin xl (only made me more anxious). I really need something because i overthink too much and im not spontaneous like before.