I suggest you read up on oral sex. Teasing and indirect stimulation are what work to build "suspense.". That's why she flinches -- because what you are doing very likely hurts, too much too early.

Like I said earlier, sexual satisfaction is a combination of what goes through a woman's brain along with physical activity. Running your fingers along her jawline and later along her lower curves. A touch here, a caress there. Long, slow, sensuous kisses on her tummy or thigh. You really need to read some erotica or graphic romance novels! Or go to the library, 613.9, if I remember correcly.

I'm moving this to the Adult Sexuality board for obvious reasons.