The same thing I think when I see a guy with a large penis: whatever, is he gonna be good at getting me off?
I have answered this question time and again on this site, but I'll happily reiterate it over and over: it is NOT the size that matters!
It's a fact that a majority of women cannot orgasm from intercourse alone, especially missionary position. Those movies where the guy just climbs on top of the girl and suddenly she sounds like she's in the throes of some sort of religious fervor? (Oh God oh God,etc.) Yeah, those are lies. And IF that's how your girlfriend reacts, either you're one lucky duck, or she's faking it.
Short biology lesson: did you know, most of the nerve endings in a penis are concentrated at the head? Women have just as many nerve endings down there as guys, the difference is, most of the nerve endings are INSIDE, with only a tiny portion outside the body (the clitoris.)
Actually bringing a woman to orgasm takes some dedication, and focused attention.
My advice to guys with smaller penis? (Peni?) Get good at oral. Insist on going down on her. Get her off before you get anywhere near intercourse. When you're having sex with her, stimulate her manually (with your hand or a vibrator, for example.)
Small dicks DO NOT matter. Big dicks are no better at getting a woman off than small dicks. And girls out there, this is a lesson for you too: STOP faking it, and spreading this myth that the best way a guy can pleasure you is by being huge! As long as they think the size of their equipment is all that matters, they won't put in the actual WORK required to get you there!
You asked for details!