I have the same problem. I dont mind the app, it's similar enough to RIF, but the fragmented communities are confusing, especially since they already are much smaller than their reddit counterparts. I mostly subscribed to specific and thus less populated content, like certain games and had no interest in the big places like r/gaming, but the comparable lemmies I found look fairly empty.
Then again, I would argue that right now most users are still on the fence and only early adopters made the switch, I'm curious to see how it'll evolve within the next 6-12 months.