Why does my hurt after ?

I've only had with one person, and that is my boyfriend right now, and I'm his first as well. We have a lot... On weekend we had nine times, and it never hurt. Now though when we first start having it hurts for awhile. The pain will go away after we've been having for like ten minutes. He is decently large, and it feels like his is still pushing up against my cervix. I think that we rush into having sex, and I'm not fully lubricated yet. Is there any other reason why my could be hurting?