I think you might have trouble finding an agnostic AA meeting because that would that AA meetings would first have to define themselves according to a specific religion, which they refuse to do.
That said, 12 step is very elastic. I went through it and I'm an atheist. When they talk about a higher power you can conceive that in any way you like, just something bigger than you. It could be your family, nature, whatever. Don't get me wrong, I have no doubt AA started out as pointedly Christian, and in order to stay relevant they have--- like the Church itself --- reinterpreted their mission and changed their language to adapt.
Came across this at supportgroups.com about atheism and AA--
Click Here to search for a treatment center in your state that is right for you.