Not saying that this is your problem. But, low and left is sometimes a "flinch" factor.
Yep, it could be a mental thing. Not sure if I am more nervous shooting my carry gun thinking that I really need to do perfect with it, then pull my shots or what the deal is. With the Glock 30 I was shooting I was dead on, I could put it within about a half inch of my aim point. I am assuming it is some kind of mental thing. No over thinking it with the G30, just shooting the gun. Then my carry gun, I probably get nervous thinking I need to perform real well then BLEH my shots. I have only been shooting for a little over a year and can't afford to go very often. It is a work in progress that I will get a handle on one day. I can only get better.
Last summer I was often shooting very low and left with any handgun I used. I know I was flinching. At least I have lessened the flinch because I am closer to center now, I just need to keep practicing and tighten up my groups. Not like a bullet in the right lung isn't going to make someone think twice anyways right?