Kitty,
I have experienced the same problem. This may sound odd...but if this is a newer relationship you may just be getting used to his size. It's happened to me before and when we started having sex, especially rough sex, I bleed also. Try to have him ease up a bit until you can slowly adjust to his size. Now, your anatomy may not be compatible to his anatomy and if you continue to have rough sex, you may not see the problem diminish. If that is the case then you may want to have him be a little bit more gentle. (I know that may suck)

Lube will always help penetration if you experience dryness and so on.
If I may add....since you are almost 17, you are only 16 now. You are being extremely risky not using a protection. Good for you for being responsible with birth control, BUT you SHOULD being using a condom as well. Are you certain you know his sexual background? You are playing a very dangerous game not using a condom. Please don't allow this practice to continue in this relationship and future ones. I know you did not ask for advice in this department but as a woman much older than you, I feel responsible to guide you into safer sex

I have seen horrible outcomes and do not want you to see them as well. Good luck to you.