Sorry. I'll have to get on the stick with these definitions!
Asativum has it about right. I've only ever heard this phrase in central PA. "I feel my nerve" means, roughly, "I'm too embarrassed," or "I just couldn't!" As in "I can't just go up and introduce myself to her out of the blue! I feel my nerve!"
The first time I heard this phrase, all I could think of was the literal meaning. Eew. After I heard it a zillion times, I got over that.