I think what you are missing is two elite trainees at young age. I see one in Tero but he is 8 potential, what took me to NBBA last time around was having two guard/sf type of trainees in Eckert and Campoy, and another high OD guard next to them, then just purchase salary efficient bigs.
NBBA is a completely different animal where teams are usually tanking games for cup, buying high salaried players for cheap, and with massive weekly income so I would say DII is actually the hardest league out of all given the financial constraints.
Good luck!