Quoting big interior repaint jobs in Jersey - what the hell am I doing wrong?

Been quoting interior painting jobs around north jersey for 5 years now, and im consistently underbidding by at least 20% on the big ones. Just did a 2500 sq ft house, quoted $6500 for two coats of benjamin moore regal select, but materials and labor ate up way more than expected cuz of all the trim work. Anyone else in the northeast dealing with this crap? Feels like im leaving money on the table every time.