Join the club, raise you hand if you ever shot over a critter! Its easy to pick a spot and then not concentrate and follow through on that spot. What helps me up close is to use a straight draw instead of a swing draw. I start by holding the bow arm high and "gun barreling" down the arrow and then lower my bow arm as I draw. Try it and practice close targets more.
If I do all my target shooting at 20 yards then my instinctive sight picture or peripheral sight picture or whatever you want to call it or maybe its just body memory, anyway, it shoots the 20 yard shot on auto pilot.
Keep at it, you will get deadly up close.