FictionOnlyReader
I would also suggest time-skip to preliminaries of 3rd year. Maybe let the next few chapters be SOL or some GoM insight. Or breakthrough in assimilating things he copied from training camp. Or you could show us some high school couches/scouts trying to recruit Shun. And after that go to the 3rd-year competition. Honestly, I am really looking forward to the high school arc.
I think that It is better for Shun to go somewhere else in the 3rd so he will miss the nationals. (maybe let him go to be a exhange student to the US for a semester or something. With that he can still have a half year of romance with satsuki) Also i think that the whole high school arc would be pointless if Shun beats the GoM in middle school. What would be the point to continue the story if he can already defeat the complete GoM team in middle school.
yeah try other sport perhaps soccer (see how ball dribble (soccer ball) bypass many opponent can upgrade his drive in pass or other move skill) maybe create spinning dribble or bouncing pass so even u don't have kuroko phantom pass, u can still pass with irregular pass by bouncing (like twist serve on prince of tennis) hahhaha just imagining
I believe the slice of life chapters are a bit bland and disconnected from the story, like you are writing them just for a breath of fresh air and to make the story a bit smoother. Shun should have much more things in life that school basketball. Maybe make a little tournament of street basket in 3 vs 3 format, but not so heavy on the games themselves but more from a character development way, even with more interactions from shun's parents.