Posible to pop cherry of numerous times?

I'm a 13 yearold girl and I was wondering because me and my bf are sexually active. He is 7inches long down there and when we first had sex there was no blood but it still hurt, I think we had sex ovr 18times after, 1of the times I ***** really walk well, maybe around the 30th time we had sex, there was blood, I wasn't on my period, and it ddnt hurt...is this ok? Or is there a problem I'm not really seing?