I started using drugs much later than you. I didn't drink until I was 18, I smoked weed the first time when I was almost 20, and didn't try anything else until I was probably 25. I've tried alcohol, lsd, psilocybin, mdma, hydromorphone, and adderall. I drink and smoke marijuana on a regular basis, but I've always had a healthy respect for the potential for drugs to change your mind.
I've had problems in the past drinking too much. I always liked drinking because it lowers inhibition. I felt more loose and sociable, and I would over do it quite a bit, just because I was so much more sociable, and if I have a drink in my hand, I'm probably going to drink it - almost as a nervous habit. It was always tough for me to set limits. I would get emotional if I drank to much and if there was an argument I'd blow up at people. I enjoy drinking, and have definitely learned to find a good spot and maintain that instead of getting wasted... Most of the time. Weed for me is kind of a strange love. I used to get paranoid - and then I found that it was just my environment. When I started - I needed to be alone and just feel the experience. It took me a while to realize that. I was always wondering how people are having so much fun socially when I was just sitting on the couch thinking shit. It was almost like I was in a bubble that I created for myself, but it took me awhile to expand that bubble. It definitely used to sap my energy. I would be lethargic, but I would always blame my job (which, I've mentioned in this thread dozens of times in this thread, I abhor). I feel so wound up after work that I really look forward to a big bowl when I get home, and just jam out on my guitar for an hour or so. Its a huge boon to my creativity (especially when I'm alone). I've written a few songs, learned several instruments while under the influence - it flows much more freely.
LSD I've tried twice, and both at low doses. It was enjoyable but wasn't what I expected. It was too long for me. I don't see a potential for abuse with it. The biggest issue is not knowing what you're truly getting. I will try this again, at a higher dose and see what its like, because I've had good experiences with psilocybin.
Psilocybin I've tried twice. Both times were pretty intense, and there were points where I was very anxious and it wasn't that pleasant, but again, it was a lot to do with environment. At the time I was worried because I was alone in the dark. Again - I don't see a potential for abuse here. Its an opportunity to learn more about yourself. I had a lot of really interesting hallucinations, and was completely aware that that's what they were. The next day you feel kinda off, but not like a hangover. Over the next week I just felt like... more open, I guess? I don't know how else to explain it. Adderall just helps me focus. I take that once in awhile if I have a project I need to knock out.
Overall, I think drugs can be good if you don't abuse them. If you abuse drugs (or anything for that matter, food, sex, ego, etc) its obviously going to have a bad impact on you. Be mature and cautious, and you'll be fine.
That said, if I didn't do drugs at all, would I be more productive? probably.