M42 is overexposed. I suspect this happened during processing because your subexposures were shorter than I would have used at the same ISO and focal ratio. (I have the advantage of darker skies.)
Your stars are round which means your guiding is adequate for your subexposure duration. If you haven't already done so, you might experiment with longer ones. Reduce ISO in proportion to keep exposure the same. Back off when you begin to see star trails.
If your camera tracker doesn't have a polar alignment scope, there are other ways to get a decent polar alignment. For a first approximation, use Google Maps of your observing site at highest resolution. Here is a good article that covers several methods for polar alignment: https://uncle-rods.b...alignment party. Drift alignment is the most complicated and tedious but is the most accurate. If you always observe from the same site, try marking the positions of your tripod legs and put them back in the same place next time.
Your camera is excellent but your zoom lens isn't. If you look at stars in the corners of your images, I think you will see that they are far from round. The problem lies in the lens, not in your guiding. Jerry Lodriguss has this article about camera lenses for astrophotography: http://www.astropix....rop/lenses.html. It contains a list of good Canon lenses.
If practical, find a darker place for your astrophotography. Not having to subtract out light pollution makes a huge difference in the quality of your images and the time it takes to get enough data for a good image.