小中大
pEGFP-N1 uses pCMV IE promoter which is mostly used in mammalian cells. Never heard any report to use that promoter in baculovirus expression. Some host transcription factors may not be there for efficient transcription.
Anyhow, that vector definitely is not a good positive control for your experiment.
As far as I know, titer of recombinant baculovirus won't go up from generation to generation. You observation MIGHT be due to low transfection efficiency.
It is true in most cases you will see morphology changes in 3 days and sometimes up to 5 days.
Suggestions
1. Re-prep your bacmid with special care for big DNA.
2. Do the pFastBac-beta gal recombinant bacmid as control.
3. Start a new vial of sf9 cells.
4. Why not lyse the cells and run SDS-PAGE and/or western blot to confirm your concern of experimental failure?
BTW, what is the protein you would like to overexpress?