^Yes, but it's not too late to say STOP!
Yes, I used from 16-21. Yes, my short term memory sucks now. Yes, pot is harmful, plain and simple (not for gateway claims or anything else...it is NOT PURE! Drug dealers cut it with crap like formeldahyde!)
You are his mother. Get him to stop. 16 is not old enough to make decisions like this, his pre-frontal cortex is not developed (the part of the brain that makes rational decisions and foresees consequences for actions). You need to be his pre-frontal cortex right now. He guaranteed will not like you for it now, but later will thank you.
My son is a tween, but when he gets there, I know if I'm faced with this, my son will hate me for a bit (as I keep him home and limit access to his friends to build trust so that he doesn't break that trust again by using) but I will do what I have to to protect him until he is old enough to make his own decisons.
Oh God if only it were so easy!
At the moment it is up to school to monitor him, which they seem to be failing at. When he is at home all I can do is ask where he is going and who with. I cannot chain him to his bed. I'm not worried about being the Dragon and have been by threatening him with the police but he is 16 which legally means he can leave home whenever he likes. So I cannot come down with the ultimatum!
How did your parents deal with your situation?