If you don’t have real-world connections, I’d say the best place to start would be by connecting with other artists who play similar music. Get a Facebook and Twitter and Instagram account, promote other bands, and some will likely promote you back.
When I was doing this shit, my bands and friends cultivated a little mini-community. We supported other bands, and they supported us, even when we didn’t get along with them or like their music. Now the communities are mostly online, but I’m willing to bet the same structure is at least somewhat in play now.
I have never used Reddit because my god I’ve heard some stories (alt-right stuff, stalky stuff, the rest), and also the whole system confounds me, but Jesus talk about community-building. I’m sure there’s a sub-Reddit of a sub-Reddit that is entirely devoted to the exact demographic you want to reach.
Seriously, follow the Ariel Pink and John Maus or Crystal Stilts fans and there’s probably an active group — under, /m/ under, like, /fucking-alt-m or whatever/, under /indie/ under /bedroomindie/ that exists solely for discussion and discovery of
“bands that sound like late-‘80s/early-‘90s lo-fi but also kinda sound newish but not too new.” 
Just spitballing here.
Also (and I’m not sure why this wasn’t the first thing I asked) WHERE DO YOU GUYS PLAY? When is your next show? If your answer is “we don’t play live,” maybe because you don’t think you’re “there” yet, well... get there. Like, before you pay to have your shit uploaded to streaming services, get your live shit together. Being available and ready to play a show can be a HUGE boon. Having that information out there for promoters and bands looking for touring partners or opening acts... man. Yes. That is super important.
Just say something if any of this resonates or sounds good to you.
ETA: Crystal Stilts not Crystal Castles. The post-punky ones, not the electro-bang-bang rapey ones