9 Hours is too much, what you are doing is called oversleeping, you are sleeping so much that your body wants to just sleep more, its the reason they say "get your 8 hours" not 9 or 10 or 11 or 7... you can train your body to live on anything under 8 hours eg 5,6,7 but anything over and you will be tired again
You could need to take vitamins or have a better diet. It could be part of adolescence if you are that age. If you drink anything caffeinated, stop. That often has a bad effect on me, at least, similar to the one you describe.