if your hydrometer readings were correct, you'd be getting 65% efficiency, not the 75% you're looking for but better than 55%. Have you bought grain from Brewmasters warehouse? I know that with them I normally get 72-74%. also what is your post boil volume?
Of course bigger grain bills can cause your numbers to go down a bit. One thing to look at would be to get a grain mill and grind your own grain.
That makes sense, I guess I need to use a different calculator/do my own equations. I've been in the market for a grain mill, just waiting for the funds and the moons to align. Thanks for the help, glad to see I'm not that far off.