You should be wrecking arrows at 20 yards Pappy and forget about the broadheads until you get it shooting the way you want with field tips.
It sounds like something is loose or maybe a cocking issue if your not grouping them tighter than 6 inches off a bench. I would give you some advise but your already getting better than I could give you. I just pick up the Pheonix and she hits where I point her.I'm sure you will be just fine.