Chance are, PBZ, it doesn't have anything to do with your equipment. If she's young, she's likely inexperienced and doesn't know what to do. She's probably a little frightened of sex in general and may even have some earlier formed notions that oral sex is bad or unpleasant. Girls tend to be more cautious sexually anyway, especially at first, and she may feel like you're a little too eager in that area. It could be almost anything, and truly none of those things have to do with your penis at all.

You have to start with getting her to initiate touching you with her hands, then work from there, practicing the patience and celibacy of a monk for a time. You can plan now to be frustrated as heck for a while. Just give it time.