PUBLIC MARKS with tags aikiken & cut

I've become obsessed with my sword cuts as of late. One thing has been driving me nuts for well over a year. When I swing my sword, watching my cuts in a mirror, I just can't seem to get the tip of the sword to go straight. It moves, ever so slightly, side to side as it goes down. It's super minor, but I can't stop thinking about it, which is probably making it worse! What I tend to do is stare at my own eyes in the mirror and try and swing the sword to pass between my eyes in the mirror. I think I'd equate it to shooting a rifle or a bow and arrow and having the shakes. Has anyone else experienced this and been able to steady yourself?