This indicates to me that BDSM may just not be for you. Either that or your relationship is just not at the point where you're comfortable enough to do these things. BDSM is something that you're into almost instinctively, or it takes a lot of trust, communication, and warming up to it gradually before getting into the hardcore stuff. Talk to her and let her know that you need some patience and guidance. It's great that you're generous and eager to please, but this is a very new world to you and you need to go at your own pace. If she genuinely likes you, she will be happy to teach you the ropes at your own speed. After some time, you'll either get into it or just feel the same hesitation as you do now. And that's fine, it's not for everyone. But if that happens, you'll have to bring this up to her, and decide together if you want to compromise or find other people more suited for yourselves.