Was one of them in Chicago? I think that's the only ALA conference I went to and it was because I was job hunting. I did go to a few smaller regional ones elsewhere though. Yeah, it's a pretty enormous conference.

And you're right that when you're depending on in-person meetings it's much less likely you're going to be connected with people who like doing the same thing you do because it's already a big hurdle that they're in the same fandom.