Not only are you hitting your chips fat and thin, but you're missing your target even when you catch the ball clean.
Make sure your setup is correct and then keep the shaft in line with your left arm throughout your stroke.
HOW TO DO IT
Lasso one end of a piece of string (about four feet long) around your left shoulder, and the other around the base of your left thumb. Make sure the string is taut and forms a straight line.
Make a few practice strokes while trying to keep the string taut and your left arm and shaft in perfect alignment from start to finish. The string will immediately go slack if you make a poor backstroke, or if you fail to incorporate some body rotation throughout your motion. In this drill, a slack string is the equivalent of catching the ball thin or fat.
Maintaining this straight line is important it guarantees that your hands will be ahead of the ball at impact to produce a downward strike. That's when your chips fly straight and roll out like a smooth long putt.
HOW TO SET UP
Set your left arm and shaft in a straight line so the string is taut.
Set up with slightly open hips and get ready to rotate them back and through.
Make sure your left wrist is flat and your right wrist is bent--and keep them that way.
Play the ball off your left ear and press your hands forward to align the shaft with your left arm.