Jesus Christ Anon I sincerely hope you are trolling.
If not, sounds like your problem is more confidence than anything. If you already have girl friends then you have proven you can actually talk to girls in a constructive manner, which puts you above 99% of this board. Just fucking go talk to girls and forget about the size of your penis. No one is going to ask you about your penis on a date and you certainly should not bring it up.