As for ONLY dating girls who have read Homestuck, you're certainly free to set whatever standards you want, but in MY opinion you're limiting yourself rather drastically. There are probably tons of girls out there who WOULD like Homestuck but have never heard of it before—entirely reasonable, as it's NOT the most well-known thing in the entire world, and most people stumble upon it by chance or proximity or recommendation.
To give you an example, when I was in high school I was pretty into Kingdom Hearts—it was my Homestuck at the time in terms of me being an obsessive fan. But if I only dated guys who were also big Kingdom Hearts fans, I WOULD HAVE NEVER DATED ANY OF MY 7 EVIL EXES. I'd still be single, because it was an unreasonable thing to expect everyone else to love or experience, and I'd be here complaining that nobody meets my Kingdom Hearts-based dating standards. Instead I DID date them, and it worked out fine, because I'm perfectly capable of talking about things aside from my fandoms, and so are you. And as it turns out, I made at least a couple of them play the Kingdom Hearts series while I was dating them, and they liked it too! They never WOULD have if I'd written them off from the start.
And some of them WEREN'T interested in Kingdom Hearts, even after I showed it to them. That's also okay, because at the end of the day, there was still plenty else we could enjoy together, and plenty of other shows/movies/genres/topics/books/whatever that we were able to bond over, or argue over, or make fun of. Not to mention plenty of activites that weren't based around the consumption of media at ALL.
Think of it this way—say there was some smart, pretty nerdy girl who was cool and who thought you were cute and funny and a good cook—BUT you had never read her favorite book <book title> before, so she wouldn't even consider you an option. It's certainly her RIGHT to do that if she wants, but doesn't that sound at least a little silly and arbitrary, especially if she doesn't even tell you WHY she's writing you off? Maybe not, but at least to me it does. People are SO much more than their favorite webcomic or movie, and people can also date and still have differing tastes. If you're looking for someone who's into ALL the same stuff you are, you're going to have a very limited pool to choose from, and probably going to be looking for a really, really long time unless you're lucky.
Some people like dating people who share the majority of their interests with, and that's totally reasonable. I do too to limited degrees, you certainly need to have something to talk about! Personally though, I PREFER to date guys who I can share some new things with—and vice versa! I've found SO MUCH cool stuff because of the different things my boyfriends have been into, which never would have happened if I'd refused to date them for liking something different than me. Hell, some girl may show you something that you end up liking way MORE than Homestuck, and which you'll make your new standard for what people must like in order to date you. Or whatever your standard was for dateability BEFORE April 2009. Or whatever your standard might be at other points in the future when you stop being as into an obscure webcomic that ended in 2013.