Similar experience here. Increased sports participation, increased workload, and skating by on old work habits. I think I was expecting too much in terms of what ds would be able to do independently. Also the same with science. I just went back 4 chapters because I realized he was not grasping the material as well as he should. This was where I discovered he skipped 2 sections of a chapter. Everything is making more sense now.
I definitely fell down on the scheduling portion, too. I should have made up a weekly schedule from day 1 and insisted we stick to it.