I have severe performance anxiety

PU is the same way, if you spend to much time thinking ahead, or thinking what might go wrong, or thinking about her feelings toward you, then YOU ARE NOT IN THE MOMENT. A chick KNOWS when you are not sharing a moment WITH HER.

Try asking question and use some Reflective Listening in order to FORCE you into the moment by concentrating on her words, and her body movements, and facial expressions.