Is a girl suposed to really want sex

Both genders have sexual urges (although it's common for society to pretend that women's are less strong). Either way, don't just go out and jump someone random. Make do with masturbation until you're sure you are ready for sex.

My ex gf was the same way we had sex all the time. Sometimes I wasnt even turned on and she would hop on me and take all her clothes off. It was some crazy times we did it everywhere too. Too bad she doesnt live closer I prob would be there right now

How young is young girl?

This is very normal especially if your young...puberty makes your hormones go out of wack and makes you horny as crazy...you'll most likely grow out of it and even if you don't its normal :)