I'm 13, but I act and look like I'm 17?

Hey! So I have a problem. I'm 13, going into 8th grade this August, but it's like I'm fricking 17. My sister is 17, and wherever we go people always think I'm the older one. One time my sister and I were on Omegle (a website where you video chat with random people) and people guessed my age as 21! So, yeah, clearly I look way older than I am. But not only that, I act way older than I am too. I think a lot of this is because I spend a lot of time with my sister (17) and my brother (20). But I listen to like hardcore rap like Tech N9ne and 2pac. And this sounds awful... I know. But you know how when you're 17, everyone smokes weed and it's not a big deal? Well that's what I think like. I went to the Wiz Khalifa concert with my friend (who's my age) and she was freaking out about how everyone was smoking but I just took a deep breath haahha. And I swear way more than I should too. And everyone in my grade is "in a relationship" which I think is so ******* stupid. Like they say "I love you" after an hour and they "go out" for like a week. It's so stupid and it makes the girls look like sluts because they have a new "boyfriend" every week. All I wanna do is party, but when you're in middle school there are no parties hahah. No one in my grade thinks like I do and would freak out if they saw someone drinking or smoking. And I fit in perfectly with high school kids, it's weird. Like I was hanging out with this 21 year old (he was teaching me how to long board. Nuthin creepy haahha) and he was so much more fun to hang out with. Plus my sister knows this freshman and she says he's like my long lost twin haha. We're not even friends on Facebook but we've had the same status like 5 times. So basically, I'm wondering what to do? I hate being friends with middle school kids! They're immature, annoying, and just plain stupid. No offense if you're in middle school, I just mean like 99% of them :) I can't chill with high school kids because I don't know where to meet them and what kind of high schooler would want to hang out with an 8th grader? How do I meet cool, chill kids to hang out with this summer? Thanks a bunch!! XOXO