I generally test in the 80% range for extroversion, but I still feel the same way sometimes.
If it is especially cold atmosphere to me (i.e. public speaking by ME) I can really feel anxious. Cold sweats and everything. I have read that ENFP's are the most introverted like extroverts and the personal growth pages stress that we need time alone to stay on our paths.
Probably didn't help any, but ya, I feel you