If the gun is too big in the grip area, a double stack 9mm or a S&W N frame revolver, often the shooter hold the gun with their hand on the side of the grip, the backstrap not centered on the palm with the wrist and arm bones aligned and the trigger is pulled sideways. When the trigger breaks, the gun will move as the trigger over-travel allows the uncontrolled movement.
Make sure the gun fits your hand, make sure your grip is such that the barrel, wrist and forearm are aligned. Then use the pad on the tip of your trigger finger to press the trigger straight to the rear. If the trigger reach is too long for your hand/fingers, get a shorter trigger [easy to do with a 1911].
Also, get a GripMaster hand exerciser and strengthen your fingers. You can squeeze the 3 fingers and hold the pressure and then squeeze the trigger finger independently, a very good exercise.