Making it a taboo for a furry to date a non-furry is silly, and thankfully that hasn't been my experience, and I'm sorry if you've experienced that.
As for the reason why it's common to find dates within the fandom? We have a culture that's very open, often intimate, and extremely weird to many outsiders. Also Tinder fucking sucks and Grindr isn't much better, the fandom is a better way to meet people than those apps.
Try to make small steps. If you're comfortable chatting with people online, get to know a few before the meetup. If you become friends online there's a good chance they'll want to use the chance to get to know you in real life as well, at least in theory.
The important part is to just not stop trying. It will get better when you're 18 most likely, but beyond that the only way to get better at socializing is to do it. No one will break your shell but you, I wasted a lot of years thinking otherwise.