All good advice there.. get her worked up first, I think that, if I remember correctly, that the clitoris is extrememly sensitive at the start of the period of sexual intimacy..
My fiancee is similar at times.. rather than have direct stimulation with your tongue.. just roll your tongue over the hood that protects the clitoris Do circles around it, just don't touch it directly. And ask her if it feels good.
Also I agree with toasty if she's getting turned off that quickly. Perhaps she is abit squimish about doin that. Some girls fear the thought of what their SO might think about the odours and tastes of 'down there'
Allrighty, hope it was of some use