I don't think you can predict your child's weaning age.
Both of my children were frequent nursers. BUT, DD much more so than DS. She also took much longer early on. DS was a "frequent" nurser at 12-18 months (compared to most) and still nursed through the night, but DD nursed much more often. BUT DS has kept a more even pace (a lot, probably because I was pg with DS when DD was 24 months). So, while DD was a more frequent nurser until at least 18 months (and to clarify I mean 30 (?) times a day versus 20, lol), at 3.5 the situation is totally different. DS nurses probably 6+ times daily now (he will be 4 in August) while DD was sleeping all the way through the night at this point (so probably nursing 3 times daily).
I don't really know, though. DD's good friend who was the most high needs child I have encountered weaned on her 5th birthday and her brother is still going strong at 4.5 so
I really tink you can't tell *too* much.
Both of my children were frequent nursers. BUT, DD much more so than DS. She also took much longer early on. DS was a "frequent" nurser at 12-18 months (compared to most) and still nursed through the night, but DD nursed much more often. BUT DS has kept a more even pace (a lot, probably because I was pg with DS when DD was 24 months). So, while DD was a more frequent nurser until at least 18 months (and to clarify I mean 30 (?) times a day versus 20, lol), at 3.5 the situation is totally different. DS nurses probably 6+ times daily now (he will be 4 in August) while DD was sleeping all the way through the night at this point (so probably nursing 3 times daily).

