Just a few more thoughts for you -
He doesn't like big crowds or noise and likely has sensory issues.
FWIW, my dd with vision challenges also didn't like big crowds and was extremely sensitive to noise. In some ways, I think the visual challenges led to uber-development of both her hearing and sense of smell. She is still extremely sensitive to odors, but was able to deal with large crowds once we had her vision challenges remediated. She also appeared to be a highly sensory challenged child when she was young, pre-vision diagnosis. Much of the sensory behavior was also tied back to vision.
As soon as I pick him up from school he buries his head in a book to relax from the school day.
Rather than the reading, the need to escape/cool down/etc is a red flag (just my perspective)... many kids are tired at the end of the school day, but most kids don't need to "relax" when they come home from school at the end of the day. My 2e ds had a similar mode of operation (but different type of escape) when I picked him up from elementary school prior to his diagnosis and getting appropriate accommodations in place.
Best wishes,
polarbear
