I used to do this alot when i was in my early teenhood years,
I think it is just a crock of crap that people say oh ive got a bigger penis then you oh i have a large penis etc etc. People like that are a watse of space and are really insecure about their own penis size.
In the end i think your penis is as good as the girl u make love to thinks it is

If it makes her happy you shouldnt be to worried.