I definitely relate to just about everything you said, except for the "talking with others" while you are out part. The only way I can remotely have a decent conversation is if I'm at home or maybe a couple of other places, and sitting still, and ONLY with one or possibly two other non-threatening, relatively slow speaking people.
I've always been kind of like that though. Very much of a thinker, and daydreamer. I always did very well in school, so I was never flagged as having any potential "problems." And I could always function well in structured settings. But I never could hold a conversation while in motion. Not in a car, not while running for track, not even just walking in the hallways at school. I always thought that was strange.
But I used to be able to thoroughly enjoy nature, being alone in the woods, taking long walks through the park, just staring out at the lake at our family's cabin. Not being able to experience nature anymore might be the worst part of this illness for me (other than the insomnia and frequent bouts of weird paranoia). For many sufferers it is the emotional disconnect from friends and family that is the worst. That sucks too, but I've always been rather disconnected socially and emotionally from others, so I didn't lose much in that department when the severe DP hit.
I, too, stay at home most of the time, despite hearing from everyone that I need to get out and try to do things. I did that for the first 8 years after my symptoms flared, and it's just way too depressing most of the time to just stare blankly at nothing when you are out with "friends", or to be unable to experience anything you are "doing". It felt like I was just doing things to try to placate others. And of course they would feel embarrassed if I broke down in tears or got frustrated and irritable by my inability to feel anything at all.
So to sum up, yes, I definitely relate to this. Very well.