Women are taught to feel shame over their bodies exudations - just look at the entire 'feminine hygience' industry, right?

I think you´re on the right track - it´s difficult for a woman who isn´t comfortable with her body to relax enough to really get into something like oral sex - be sure to lay on the verbal reassurance/encouragement - i.e. 'I love the way you taste' 'you look like a beautiful flower' 'I feel so close to you when you trust me to pleasure you this way' 'this is so hot'

If the oral stimulation is combined with tried-and true hand stimulation, that might help, especially if you add the oral after she´s on her way with the other (thus maybe a little less inhibited)

Personally, I always prefer the laying on my back, knees over his shoulder position - she might feel less exposed/vulnerable if you´re both covered with a sheet (although you might feel more suffocated ;) It´s also fairly familiar ...

That said, something that always works for me is if the man puts his lips in an 'o' and softy encircles the clit, sucking it in and out GENTLY (it´s a pretty sensitive spot, after all)...

Good luck!

You know what? I believe we are married to the same woman.