We have talked about this before and she says she'll be fine, but she's never seen how big I really am, and I dont think she realizes that it'll hurt her the first time. Don't take this the wrong way, this is not aimed at you but at we males all over the world. I think that it is funny that men measure themselves. It is clearly more proof that they care about their size 200 times more than women do. But, you do have an interesting point.
More women complain about someone being too big than they do about someone being too small.
I wouldn't worry about it, but just listen to her and take it slow. It is going to hurt the first time weather you are 5 inches or 10. The first time a girl has her hymen broken, it is going to be painful. I don't think that you need to be worried, everything will probably be fine. More than a year ago I met a wonderful person I am having the best relationship I ever had.