RE: How long are your practice sessions?
learning back tension i blank bale with shut eyes about 10 times then shoot some 20's and 40's and then about 10 more blank bales. if you want to get better i really suggest closed eye blank baling (5 yards). aim, close eyes, wait, release. you'll figure out if you've got a steady full draw position.
another good thing is to get to your 20 yard distance, draw, get into position for release, close your eyes and count to 8. then open your eyes and see where you are aiming. if you're not dead on center you need to adjust your stance until you are when you open your eyes. consciously you'll correct your aiming with your eyes open, but it would be better if you didn't have to.