I'm pretty confident it isn't social anxiety. I'm great at talking to people I'm comfortable with, almost to a point that I love socializing with them. With people that I've just met, however, it's different.
Your rebuttal doesn't really make sense as a defence though. If you are OK with people you know, but not ok with new people - that sounds more like it would strengthen the "social anxiety diagnose".
However I am sure it is not introversion. Introversion is not related to social interaction. https://en.wikipedia.org/wiki/Extraversion_and_introversion#...
Don't get me wrong. I can see myself very much in your description, almost to a tee. My point is just that I think you are mistaken in your definition of introversion, and that you should read up on it and the common mistake of thinking it is the same as e.g. shyness etc.
(For what it's worth, I've seen quite a few threads like this that seem to get responses saying that the OP has such and such psychological condition; it kind of astounds me how so many people a feel that it's prudent to provide a stranger with unsolicited medical diagnoses based on a couple paragraphs they posted on the internet. You're under no obligation to respond to them, so feel free to disregard them if you'd prefer to.)
I was kind of surprised by the many comments saying I suffer from social anxiety, but I figured their lack of information about me lead to their diagnoses. So, I hope they think otherwise after my responses and instead provide great advice like yours.