My experience around here (Durham, NC) is that many "closed" AA meetings insist that only those who identify themselves as alcoholics or as someone who "has a desire to stop drinking" or "has a desire not to drink today" are allowed to attend. I wonder if, since I've heard that most people who have any kind of substance abuse problem are likely to have problems with any OTHER substances, you could just say you have a desire not to drink..assuming that's true.
I would encourage you to get to any AA meeting you can, and remember that while they do limit discussions to alcohol, most of what's discussed about alcoholism could easily apply to any other addiction.
Best of luck to you.