When I was younger, I was much like the OP. I really resented being interrupted and asked what I was thinking about or why I looked sad, or being prompted to smile.
Nowadays, I've resolved that problem by treating the situation as an opportunity for a brain dump: I tell the other person what I was thinking about right at that moment. Sometimes I have to clean it up or be general so as not to shock or be socially inappropriate, but in general I really do tell them what was on my mind, sort of as an anecdote. Even to total strangers.
And usually people are interested. It reassures them that I'm not in a foul mood because of them; and it makes me seem more transparent (and therefore non-threatening) because they see me opening up easily to them on demand. And personally I kind of have fun with it. It's kind of a surprise to me what comes out sometimes.
But that's how I've resolved that situation as I've gotten older. Furthermore, it suggests to me an answer as to why that situation was such a problem when I was younger. It was because I imagined some kind of high barrier or wall between "me" and "them" that I felt shouldn't be breached. Now that I've gotten in the habit of breaching it, I find it's kind of fun to let people in on my thought processes. I think it gets back to the "self-monitoring" thread, and perhaps concerns the issue of what we consider our "true self" (and how zealously we guard it from the outside world).
Just my two cents, of course. Oh well, off to bed.:zzz:
