220 sandpaper is way too coarse for what you want. You can hit the first coat or so with 220, but you need to kick it up to 400 pretty quickly. I even push to 600 grit for a smoother look.

Buy 3-M Wet or Dry paper at your local auto supply store. Wet sand it after it dries thoroughly. Dry it completely before the next coat.

With a primer that fills very well, you may get it to your liking after 5-8 coats. That depends on how many scratches were put in it during the bondo fill and initial sanding. If you use too thin of a primer, you may never get there.

Final thought. Flat paints show flaws much less than polished, glossy paints.