Selective Social Anxiety? Or just an irrational fear of strangers?

So, this might sound strange, but I don't feel particularly anxious about being on camera, being on the radio, giving an unprepared speech for a decently sized audience, teaching or most things in an academic/professional setting. I may get some butterflies/adrenaline, but for the most part I seem to be more comfortable than average in these settings.

However, get me into a social situation and it all changes. Put me in a small house party where I don't know most of the people there and I'm terrified. It's very difficult for me to talk to strangers in social situations and I have to know a person very very well before I can relax and talk naturally and be comfortable.

Apparently, that is not the norm, as I've had people not believe that I can't make friends easily or navigate purely social situations unless it's with people I already know. I even used to have a difficult time going through drive-thrus or calling to make appointments etc. because it meant talking to strangers. When I lived in a city and there were more options for stores, I would have difficulty going to places that were very large (like Walmart) or places that weren't my usual place because I didn't know what to expect and maybe even the whole too many people (although I think large stores came from my fear of getting lost).