Do you know what the biggest sexual organ is? The BRAIN!

And honestly, the most sensitive part of a woman's vulva--her clitoris--won't be affected by how big or small you are. I know pornography makes men think women get pleasure from being stretched to the limit by some huge thing, but real women don't work like that. Focus on connecting with her heart and being confident--and I mean that in the sense of real confidence, which is not acting like you're fearless or perfect, but just being yourself; admit when you feel vulnerable or scared of rejection, if she cares for you, she'll want to help. I don't think most men understand how important emotional connection is to helping a woman enjoy sex--being a good lover isn't really about pushing the right buttons or technique in the head, so much as it is about being caring, asking how you can please her, and creating a connection with her heart through little things in your ordinary day, not just when you're ready for sex. Personally, I've seen a larger penis that I loved and thought was very beautiful, and I've also been madly, passionately in love with a man who'd actually had to endure a penectomy as part of cancer treatment, and he was every bit as beautiful to me (not to say you don't have a right to your fears, but think how full of doubts HE was)--and you know something? It didn't matter, because I cared about him as a whole person. Bottom line, some women are obsessed with penis size, and some men are obsessed with breast size, but would you really want to be with somebody like that? There are plenty of amazing, wonderful women out there--Hold out for the woman who's right for you & she'll love you as you are. Also, you know the most sensitive part of the vagina is the first two inches past the opening, right? If you're happy to supply her with oral sex, that'll get everything engorged and you should be just fine. Don't stress!

And PS--re the part in your post about not being able to "pound away the way some girls seem to like"--SOME and SEEM are key words there. As a woman, I would feel like curling up and dying if a guy just pounded away at me, but I also thought for a long time that that's how men ALL wanted sex to be--tell her you want to make love to her and for things to be sensual and gentle, and maybe even look into some Tantric stuff--I PROMISE you, not all women consider a giant wiener thrusting away at them the gold standard for sex!