Youth groups are a good thing, I did them around your age, doing them a bit now still, too. I'm slightly older than you, and while I love a fair share of the members here, I feel the same concerns and issues many times. For instance, my issues right now are getting my first job in a year, issues women face in the workplace because we are women, and how to handle young, heavy sexualized young men. This is rather different than transitioning in the workplace, telling a wife, or relationships of those older than myself (due to experience and maturity of both parties), etc.
To answer your question, there's another site I know of that has a teen section, but every post has to be mod approved, no matter what. Its members also often skew older than here, and I find the design to be a bit garish. Not really the best option, for these reasons. Not that many would remember it, but years and years ago, this site had a teen section. Wish it was still around, to be honest. A teen specific page, it'd be a great idea, too bad there isn't one, or I'd be there quite my fair share!
As someone who dealt with, and mostly finished, most of this stuff in teen and just past teen years, if any of you teens and near-teens need help, have questions, or the like, I'm open for them, and all ears. Most anything I can answer you about, except SRS experience (which should change sometime next year). As a little foreground, my high school was small (600 students overall, 130 some in my graduating class), but extremely accepting. Much easier to talk with, get along with, etc. after transition, especially the other girls. Thus, I can't answer questions about larger high schools as well, but I'll try my best to answer them, using my college's medium-large size, as perspective.