You might consider re-asking your question using different wording. It's not clear whether you are a DIY-er, such is against the rules on this board, but as far as I am concerned you are not proven to be.
Manual D is the really professional way to design ducts. I wonder what percentage of HVAC guys-for-hire have used it in the last year. Another tool is measuring external static pressure, which combined with a pro's opinion can tell you a lot about overall adequacy of your duct system. It cannot shed any light on room-by-room issues however.