Yeah I think your interpretation of what you're going through is very good. It sounds like too much all at once, after being shut in for a time. I would do what you are thinking, to just take it slowly, and allow yourself to become acclimatized again to the sun and all the stimuli.

I have suffered from being highly sensitive most of my life. I found that I had to just do what I could do, no more or less. Over time I have learned what I can handle and what is too much for my at any given time. I have had to be very caring with myself, and not let the opinions or pleadings of other people sway me into doing things I know are too much for me. It's been an ongoing balancing act, and I have learned a lot, and continue to do so...