What is up with the way teenage girls dress nowadays?

I agree. I'm a 13 year old girl and I am ashamed to say I am. My school isn't that bad with girls dressing like that, but there's this one group of girls in my grade of like 5 or 6 girls that dress and act like sluts. You know? The type that can't be seen without a boyfriend or with their boobs and butts hanging half way out? I hate that group of girls. The people I hang with only wear shirts like aeropostale that cover everything up, and shorts that aren't any shorter than mid thigh. I'm proud to say I don't dress like a prostitute.