Re b) “.. maybe you need more novelty” - do you have kids? Time flies when you have to focus most of your efforts on someone else than yourself, even if every day is something new.
Meanwhile, the very-novel first few years with kids seemed to go by in a flash. A month feels about a week long to me, now, and has for years.
For me the effect seems disconnected from circumstances, but connected to age—years had been feeling subjectively shorter for quite a while before I had kids, even, and they seemed to just be "getting shorter" as I got older, period, no relation to what's going on.
When watching baby playing with toys in living room, an hour flies by (thankfully because usually very sleep deprived).