I spoke a little bit to the dental assistant and then the dentist yesterday (tooth cleaning). Prior to that, I spoke a little bit with a friend of my mother's, when my mother and I ran into her in the store while grocery shopping (my one weekly outing).
I usually don't have much difficulty talking to people if they're friendly and seem interested (though I never look up at their faces, so they better make it clear who they are, else I might have no idea who I'm talking to
). That's not my main issue.
Rather, it's simply not having the opportunity to chat with somebody very often, due to 1. me being nearly housebound (not mainly out of anxiety, I just have nowhere to go and no way to get anywhere and nobody to go anywhere with), and 2. practically nobody being interested in talking with me about anything I have much to say about, even if I could get out more.
(That's awkward grammar but whatever.)
So, tl;dr--yesterday. Not like it was an indepth conversation or anything, though...mostly it was about mouthwash and such. 
I do not remember when was the last time I had a nice indepth conversation about a shared interest with someone else...the last time I regularly did that was when I was around twelve. 