one thing that is really hurting you is your very low passing at pg. there is a minor ability in this game which is basically 'getting your team mates open looks' which increases fg% and 3pt%, and it is based entirely on pass/iq and is heavily weighted at the 1. you have really low passing for d1, that is probably contributing to how poor your offense is running.
also when you are in situations like yours, you need to stretch and find a couple lead scorer types to carry much of the offensive load, to make up for the reality that you can only get so much offensive talent on D prestige. try to get some guards who approach the 90 per/spd/bh mark to score for you, 3s are very efficient in this game. you can gamble on guys with green per because lp/per ratings can grow more than anything else. its not uncommon to see a 20 something per turn into 90 something, and nothing else (except lp/per) works that way.
that 90/90/90 per/spd/bh mark is probably going to be a little out of reach, that's kind of the bar for an elite d1 scorer, but that flies at A+ BCS programs and such. in your position, you can skimp on that number some, but emphasis on still hitting the per. you play lesser competition, and against lesser defenders the lp/per carries you further, where as against strong defenders the supporting ratings that seem to help you get open, not foul, etc - those become really important, too.