It all sounds pretty similar to my experience. Living with my family (parents, siblings, cousins) has grown increasingly stressful over the past decade or so, though, so I find that things are usually (not always; sometimes we get along just fine and it's fun times) worse when I'm there.

I recently did a quick-and-dirty quantifying of different aspects of my life during different time periods, and found exactly what you said about "given" social interaction to be true. My first two years of college were horribly unpleasant and unproductive, and were also the two years that I was most alone (I didn't recognize this and was stubbornly clinging to individualism at the time); the same is true of the two years I spent at home after college (except by then I'd realized my folly; it was just absurdly difficult to do anything about it by then).

I also find myself with an irrationally negative emotional reaction whenever I so much as think the word "lonely". "Lonesome" is slightly better, and "alone" is significantly better, but I still feel strong resistance to breaking the taboo on talking about it. (I was actually considering posting to see if there was any interest in an LW meetup anywhere I can reach. I'll probably just wind up trying to make the St Louis meetups if I can level up my ability to travel independently.)