I would suggest that you ask him the following or something like it, in a
nice 'neutral' voice.
"About our talk when you were in Vegas, if you are in fact going to or are
attending AA meetings, could we kind of coordinate on which nights you
will be going and on which nights my AlAnon meetings are, so ________
(your son's name) will have one of us here with him, unless there is an
AlaTeen meeting on a night we both have our own meetings."
That is not technically asking him about his recovery, that is just trying
to get a 'schedule' of sorts set up for ALL of you.
As to if he is actually working the program or will be working the program
and getting a sponsor or not, over time HIS ACTIONS will tell that.
He may or may not talk about how he feels and what is going on with
him. Just continue to 'keep your side of the street clean' and work the
program you hope he will have some day.
I know his comments on the phone about AA gave you some expectations,
but try and keep those locked away please. It took him a long time to get
this far down into his alcoholism, and it is going to take just as long to come
out of it. No quick miracles for this one!
Love and hugs,