If I'm using the crease of my finger on the trigger, can it PUSH a shot low left, instead of pulling right? (I'm a righty.)
It's more likely that it'll pull right, in my opinion, but it IS possible. It's all in the mechanics of how your fingers work...really, they're a biological assembly of hinges, when you look at how they flex.
Put the pad of your fingertip on the trigger, centered. Practice shooting it this way.