My bad--I misunderstood what you'd typed. Watch pulling your toes and body over quite as far--you want to turn hollow and just enough to complete the turn. Also, be sure to keep tight and hollow when you turn. I had the same exact problem that you do, and I've come down on the bar many a times--just remember (as a safety tip) pull back into the bar if you go crooked--DO NOT push away. You'll have more control if you pull yourself back into the bar than you would pushing away.
Anywho--back to the blind change.
Watch the angle of turn that your post arm (the one you're turning on) has...if it's too far to the left you'll end up going farther than you need to, or you'll end up crooked.
Drills:
1. Blind turns--Do a blind change then, swing down and do another one, then swing into another one. With each one work on shifting your weight from your post arm to the other arm and evening your body out. Try to stop in handstand or close on each one.
2. Blind changes on a floor bar against a wall or with a spot.