This thread is great. I've always had a hard time deciding if I'm an extrovert or an introvert. The ENFP descriptions always suited me spot on (while the I ones did not), that's the main reason I sticked with it, but I've always had that sort of social anxiety in some settings (mostly in environments where I don't really know many people intimately) and have needed time by myself regularly, to recharge. That ebb and flow theory of ENFPs energy is so perfectly right. I feel that all the time, I can't sustain my tremendous, legendary enthusiasm for large periods.
I'm the same as you. I can have really bad social anxiety, really bad (moderate to severe). ENFP's are the most introverted extroverts so, that could be why. I definitely need a lot of space to myself. Why do people see ENFP's as these people that are super hyper & have to chat away 24/7? I really don't like how ENFP's are profiled by people sometimes.