Every psychological assessment I've done (including self-assessments) addressing this have always put me in the "introverted" area of the spectrum. But not extremely. Like many others especially nowadays, I view this as what I said: a spectrum that has some solid inborn components, but is not entirely stable. The way my introversion manifests has fluctuated in a broad variety of ways, including how much social interaction I need (or can tolerate) at a given time.
For me, I am actually much more social and extroverted sober than as a heavy drinker. Nothing has ever made me more withdrawn and isolated than alcoholic drinking. I think I'm the kind of "introvert" in the classic, psych sense of the term: not shy, but I need my space, alone time, and I like to spend a lot of time with both mental and physical activities that are done in solo. Very interested in exploring my inner world also. However, I also tend to suffer greatly if I don't have 1-2 close relationships in my life at a given time. Also, I have experienced many different kinds of anxiety throughout my life but, interestingly, social anxiety has probably been the lowest and rarest among them.
The way alcohol dysinhibited me was more like losing my sense of responsibility, being careless and distracting myself with everything but what I truly needed, and expressing a lot of my fantasy world that is normally best kept to myself or perhaps max to a therapist. Stress can also affect me this way actually.