Hey bud, calm down! I think you're right, alcohol, being tired and 6:00 in the morning can be the wrong combination. And yes, there are folks who have some difficulty with erections as a result of marijuana and tobacco products. So, you masturbate right? And things work OK right? Then there is no medical or physical reason for your impotence, and you're very correct, very few people your age have that as a problem. I'd say that several things are probably going on here. First, your two heads are very connected, therefore any thought of things not working correctly, being inadequate or in any way experiencing fear etc can effect that guy between your legs. Also, once we've had that happen (not getting it up) we become scared as heck that next time it won't work, and guess what....it usually doesn't, just like what happened to you! One more thing is that you've got that one trained to your masturbation techniques, style, grip, speed, etc and often that leads to problems responding to a vagina, which is totally different. So bud, give yourself a break here and keep trying. I guarantee you that you'll be just fine. None of us has a great "opening act" into the world of sex, sure some are better at it and have great things happen for them. Others of us need to work at things a bit, and really it takes two people working together for the best achievement! Hang in there and next time...no alcohol or pot, be rested and be ready!