I am still pumping and nursing a little for my 16-mo old and don't know when we'll stop. I agree that the benefits outweigh the hassles. The only problem for us is that the baby still greatly prefers nursing to bottles and we have big screaming fits at home (she's fine w bottles at daycare).
to actually answer your question, I figure we'll stop nursing sometime within the next 6 mo. Maybe when the baby can talk and understand more, it will make more sense to stop. It's really hard, though, to decide when, and I think we are currently in the middle of a very gradual weaning, but it's hard to see that forest for the trees of everyday nursing, pumping and screaming about bottles.
anyway, I just wanted to say congrats and don't worry about other people thinking it's strange to still be producing milk for the baby at her age.
I did accidentally learn what you will find online: that mint tea really attenuates milk production. So when you do want to stop, just try a few cups a day and it will probably help you dry up without the pain of engorgement.