Moody teenager...HELP!!!!!!!

I need help, fast! My teenage daughter Chloe is so moody and difficult. Whatever I say, she disagrees with. She got mad at me today because she wanted to sleepover her boyfriends house and thats a definate no. She thinks she should be able to do whatever her friends do. I tell her your not your friends. She rolls her eyes. I don't recall being that moody and mom agrees with me that I was a pretty good teenager but Chloe, ugh! I need some advice! I don't understand why she is this moody all the time....