Try this. Instead of the usual range commando stances you see everyone use to practise for maximun rounds fired in a short period of time I want you to try something else.
Stand legs apart, bring the gun up but do not extend your arms outwards to there max. Have a bend to them so that your elbows are hanging limp at your sides. Relax your arms and focus on just gripping the gun. Your grip should not be tight but simply comfortable. Too many people white knuckle handguns and its evident in there groups.
Your arms should not be taunt at all and when the gun kicks it should recoil upwards more than usual due to your relaxed state. It the gun doesnt kick up your holding it to tight, relax with it let your arms work as a shock absorber, and with your elbows relaxed there less muscle fatigue.
Now for trigger control. I want you to squeeze the trigger so slow your going to feel like time is standing still. If the trigger is a bit too heavy try putting more finger into the trigger guard or on the trigger.
Again slowlllllly!!! pull the trigger, the slower the trigger is pulled the better the shot especially in pistols.
Dont worry about hitting the bulls eye I want you to focus on the best grouping you can do. Once you get a good grouping I might be able to help your further.