Please help me I think I just killed are unborn child!?

I am 16 years old and my girlfriend is 15. She lives with me and she is pregnant. I love her so much. Today about an two hours ago we were having sex. It was the first time in 3 months since i had sex with her. I was in the mood so bad and she was teasing me and everything. I think I was too hard on her because she started bleeding when we were having sex. She is still bleeding. Is she having a miscarriage? Did I just kill our baby just to have a little fun with her? I am so worried I just killed our unborn child. Please someone help me.