I wish I had checked this thread sooner! I'm back in school for counselling at the moment and I've been studying personalities/typology on my own. Eventually, I'll be qualified to administer assessments (once I get my diploma). I actually also did a job search workshop on networking for introverts as a final project, so I have done quite a bit of research in the area!
So one thing I learned in my research is that introversion and shyness don't usually go hand-in-hand. Shyness is more of a social anxiety bug introversion is a way one operates. Shyness is "fixable" but introversion is something one shouldn't fix - it's just indicative on how a person gathers their energy. I'm no expert (but eventually I'll get my Myers Briggs certification)
You mentioned that you tend to recharge by spending time alone. Generally, that's an introvert quality. However, there are some extroverts who are that way as well. Everyone has both sides for instance, I'm almost an abosilute 50/50 (52% extrovert) and I'm an ENFP. Apparently, a lot of ENFP's (based on what I read) need some downtime as well just to feel centred. I used to get soooo weirded out by this but I've learned to accept and respect my need to be alone (usually to engage in my creative hobbies).
I haven't read the rest of the thread but it would be really cool what others have to say
ETA: Gaylene, that's very interesting stuff you posted! Good way to see the Myers Briggs as preferences! Thanks so much for sharing your knowledge! I always find this stuff interesting!