I believe the fat shoty is caused by not shifting your weight? you are hanging back on your back leg (right leg if your right handed) Could also be your ball position, (to far forward)
Try feeling your weight move to your left side when you swing the club, also look at getting the ball to centre or just back and see how you get on.
you might just be putting too much weight on your toes and club head at set up , which means that when you make your downswing, you get a tendency to move/rotate your body forwards towards the ball, leading to a fat
If this is the case, try (for practice) hovering your club before taking away on the backswing - this stops a little of this forward lean.