Beyond Selidor

Oh wow, my experience is pretty similar, even right down to discovering ATLA about five years after everyone else had moved on (although from what I gather about ATLA fandom, missing out on the main wave of fannish activity might have been a blessing in disguise, given how riddled with bitter shipwars it seems to have been). Dreamwidth is, indeed, the ideal space for talking enthusiastically about books.

I've not been to many conventions — I went to YALC for one day with a friend several years ago, but that was more to see panels with two specific authors, so it was more like going to a signing in a bookshop, and I went to Worldcon last year in Dublin, but those were more YA or SFF book conventions, with an emphasis on the creators of these original works. (That being said, Worldcon was full of people in transformative works fandom as well, and there was a lot of overlap between the pro and transformative side of things, with panels on fanfic, Ao3 being up for a Hugo Award, and so on.) I think I find conventions like that more to my taste than something focused purely on transformative fandom, because, as you say, I'm not really interested in talking about megafandoms, either canon or fanworks.