I recommend you learn how to give oral-sex properly and start with that after you engage in the fore-play (kissing, touching, etc). That way, you can ensure she has an orgasm before you attempt to insert your penis inside of her, and whether she climaxes or not, she'll consider you a great lover because you gave her a rocking oral-orgasm.
As long as we're whippin' 'em out; you ain't alone, brother. but you're perfectly average dude, and let me tell you something: there ain't a woman on earth that can't be brought to climax with factory equipment. They don't need a gold package and a set of dubs to get off. Believe it.
Just be confident, that's the most important thing. Be powerful, but gentle. Let her see your restrained strength. Seduce her with that, and then it doesn't matter what you use --she's going to love it.
And as an aside i had a friend in college, we'll call him Big Mike. And see he wasn't really even all that big, but, he had most of us by a few percentiles... enough that most average girls complained, and he said even a couple were incapable. (i'm trying to be tactful, i think) Anyway, he was proud of it, to be sure, but having to haul that thing around sure was awkward for him when it came time for intimacy.