You say she is skinny, how skinny?
I have noticed lack of sensation with a few really skinny ladies.
It's like you enter through the vagina lips and there's nothing inside, it's like theres no meat on the bones inside or out. The penis as sensitive as it is, cannot actually feel around inside, but insert a finger or 2 and explore. You can feel how much cushioning there is inside and how this changes with arousal.
For best sex, make sure that she is aroused and if that doesn't work, forget the creams and feed her cheese burgers.
Also kegels work wonders, even for men.
My wife caught me wearing ladies underwear and threatened to leave me.
So I packed up all her clothes
And left.