Nice going on 15 months. That's amazing.
I think whether you remain involved in AA depends on the kind of person you are. Many here on SR feel that that's all they need to remain sober. There are people in AA that live and breathe that program, as I'm sure you know by now.
For me, I need a variety of things to help be to stay sober. I get bored real easy. There's just no way I would remain sober with just one thing. I do go to meetings two or three times a week, but part of my plan is doing fun activities, going to the gym and of course SR. For me, they are equally important. Any one of these activities wouldn't keep me sober. Sometimes, it's the progress at the gym that keeps me sober. Other times, it's what I hear at the meetings, etc.
My advice would be stick with what works for you. Someone saying you're doomed if you leave AA is just using fear to keep you there, and fear doesn't keep anybody sober, IMO. John