I feel this way often. Just last night, actually. I'd spent about six hours with other humans, all together, and it always startles me how little I actually say, how they can see anything in me at all. I don't talk much, and I don't really have anything particularly eye-catching or noticeable about myself, so I've been known to just feel like upholstery, or some useless dusty thing they're forced to cart around and tolerate. The little bit I did talk, they seemed to respond to well, but I can't really be sure. I am so disconnected it's unbelievable.
I really do get where you're coming from, OP.
And, while with passion she repeats her call,
The vi'lets from her lap, and lillies fall:
She misses 'em, poor heart! and makes new moan;
Her lillies, ah! are lost, her vi'lets gone.
- Ovid, Metamorphoses