OK, first things first: most of the "what you're doing wrong" charts are based on one handed bullseye shooting. They have very limited application for shooting with two hands.

Having guided a bunch of folks through transition training to the M&P series, most of the hitting left problems are due to folks losing patience with the trigger stroke and finishing up with a hearty yank. If your groups are low left, this is almost a dead certainty. You don't mention the range. What distance? If we're talking 5-7 yards, it's probably a yank.

It's a dirty little secret that there is no magic part of the trigger digit that works for everyone. The reach to the trigger is different for almost everyone and you need to find that part of the digit that will move the trigger straight back.

I'd suggest having someone else try your pistol or going left handed (I'm assuming you're a righty) and see if the groups stay left.

FWIW, I had to move the front sight on my issue M&P.