Well I'm 15 and personally I wouldn't wear it. But that's because it isn't my style. Most girls in my school stopped going to Justice as a teenager because its for younger kids. We shop at Hollister, Aeropostale, Abercrombie and Fitch, Delia*s, Forever XXI, Wet Seal... etc. That started when we were 12 or 13. But if you like it then you should get it because it doesn't matter what other people think. You don't need to try to be like others. And you don't need to try to impress.
I don't like it much, but that's just me. There's no set style that 13 year old girls wear. There are several styles and you get to choose yours. I know a lot of girls do the basic style which is ugg boots, leggings, and a pink jacket. I hate that style. Some girls just do a dressy t-shot and jeans, which is where they wear a basic jeans but a nice top or blouse. Some girls do hipster (which I also hate but that ones super popular right now), there's tumblr which is like hipster on steroids. I did a casual rocker chic. There's girly. There's boho. sporty. And a ton of other things. Just goodly any of the styles I mentioned above and choose one