I would definitely be extroverted if I weren't autistic, as I love being around people.
As it is, though, my ability to socialise is limited and getting more so, as I need an inordinate amount of re-charge time.
It's easier on my nervous system to quietly read a book on my own.
I come out as strongly introverted on personality tests, which I think is more down to preferences I've developed from having to deal with my autism than to natural inclination.