Don't fret man. My first shot at a live deer was a doe at 22 yards. Right thru the 5 hole. (thats between her legs for non-hockey fans) she didn't flinch, so i made an adjustment and promptly pushed the arrow too far to the right, planting it right in her neck, tearing the jugular. She thrashed, sat down (I assumed to die) then got back up and commenced eating acorns out of the very oak i was sitting in. Finally she sat back down and expired.
Bottom line is, shooting out of a tree is VERY different than shooting off the ground at a block target. I routinely shoot 8 inch groups at 75 yards, but i'd never, ever, ever take a shot at a live animal longer than 40. And almost never longer than 20 yards.