How mature am I?

Hey, ever since I was about 14 I hung out with people older than me (age 18 and even up to 30) I drank with them alot and talked as if I was there age. I'm 18 now, and i'm in grade 12 (top grade). Everyone in my school seems so imature and when i say everyone i mean EVERYONE. They all enjoy going drinking and doing stupid stuff and acting like a bunch of youngsters who still take money from there momy and dady. It really annoys me. I do however have a disorder known as A.D.D but my main topic is how mature am I and is this a good thing? If I had a girl friend I would even try to have a kid soon.