Is there a way you can change your surroundings? Perhaps hang out with some different friends? Maybe if you limit your exposure to the surroundings in which you drink or smoke you'll find a different routine. That's what I'm trying to do right now. Not exactly easy when your husband plays in a rock band in bars...lol..
Probably most of us on this site used when we were in school, but so did many who don't have a problem with alcohol today. I'm just saying (in my opinion, of course) maybe if we had stopped and saw our issues long ago, we wouldn't be here today. Trust me you don't want to be here when half your life is over and you feel like you've wasted it.
Trust yourself with what you are feeling. Going with your gut is never wrong. If you have a chance to make it out before it really grabs a hold, do it. In the end you will save yourself a lot of grieve. Being young and very influential can set patterns, especially when we grow up around self-destuctive people. Remove yourself from the situation and find something else to do.