I've seen people suggest in their snowflake challenge answers that being on multiple platforms may be the way to go, since they all have different strengths and suit different formats better (e.g. privacy controls vs art-friendly, etc). It's difficult to navigate though, especially considering... all of the things you mentioned in your post. "Prioritizing a small number of close friends over The Internet As A Whole" vs "feeling like you're excluding yourself from half the fandom or more" is really, really difficult, especially when you haven't befriended those close fandom friends yet.

Lots of really good food for thought, thanks again!