You are milking (not to mention that the Glock is set for dead on aiming, not 6 o'clock). How to tell? Simple, next time you hit the range, line up and as you pull the trigger, shift your focus to your non-trigger fingers. If you find them squeezing along with your pull, you are milking.
To stop, best move is to keep shooting as before, but again, keep your focus on the squeezing fingers until you understand fully what your milking is. Then just stop it.
After that, when you pull, if you feel the other fingers tightening, stop and start again. Focus on keeping your right hand very relaxed - no squeezing - rely on your left hand for support.
If you are milking - and I bet you are - you will be amazed how easy it is to become aware of and to simply stop. Let us know...