As trishmapow2 correctly guessed, I have visual snow syndrome. Whether it's a quirk of vision or an outright disability really tends to depend on the intensity, for some people it doesn't affect their lives at all but for others it's completely disabling because they can't read any more. Personally I'm quite lucky, I'm never going to drive in the dark or be good at things that require excellent vision but I can still hold down a job as a programmer.
Possibly https://en.wikipedia.org/wiki/Visual_snow. I used to assume everyone had this but since it doesn't really affect day to day life for me it was never a concern.
Oh, huh. I definitely experience all of those, though only the photophobia is really constant. I've also got a photic sneeze reflex, so I had just always chalked those two together as a sensitivity to direct sunlight, and didn't even think to consider the dots or floaters as odd or connected.