Sleep wise, I find I've always been a 9 hour girl, and while growing up, sometimes 10. My mom & sisters were all 7-8 hour people and they'd harass me and quote studies at me, and I'd try to sleep less and then I just felt like crap.
Now studies are coming out that say 9-10 hours are more appropriate, especially while younger (teens & late teens). I'd say, try to go to sleep earlier so you're asleep more while it is dark and then listen to your body, eventually, you'll figure out what is right for you. I'm a little older now, and now I fluctuate between 8.5-9.0 hours. This past week I shorted myself twice and only got 7 hours and yesterday i felt awful.
So yeah, get enough sleep, listen to your body, and don't let anyone else tell you how much sleep you need.