Maybe you should post here about one or two or the problems you're stuck on.

Only if the LW Study Hall organized threads like that; I've been considering joining it, but never got around to it. Otherwise, I'd feel it would be a waste of people's time. There are lots of exercises I might get stuck on, and it's usually not as if any particular one of them represents a key insight to me; the answer/solution/hint to any given exercise is low-value to me, but the answer to all or most of them is high-value.

Been on Khan Academy since 2012, I think. Earned a Sun Badge and everything. (That type of performance didn't constitute my real challenge, though; I've been struggling for these two years to earn the modest Good Habits badge, to no avail to this day.)