Why am I always sleepy? F18

I sleep around 11pm - 12 am and I wake up at like 9 most days. I should have plenty of sleep and feel well rested but I feel sleepy no matter what. In the morning I feel like I can sleep forever and when the clock hits 9:30 I feel like I could fall dead asleep but I force myself to stay awake for my school work. WHAT THE IS WRONG WITH ME!!