I think there may be some problem with lubrication. What u can do is just before entering into her do some foreplay, especially if u r willing take her vagina into ur mouth and play with her clit. That will definitely make her wet, and then u can penetrate her, by doing this there is also a chance of getting orgasm for both of u at same time. That will definitely make her happy. The penis size u got is more than average, dnt worry abt the size, how u r using does matters.
And also u mentioned about her virginity, it is not necessary that blood should for the first time. Keep this in mind. And enjoy. Reply me if u r succesfull. Otherwise I will come up with other ideas.