are you sanding and then polishing by hand? I’ve said it recently too but epoxy surfaces don’t lend themselves very well to polishing. Unless you try a metal polish type, I’ve had pretty good success with that before
I would add a few papers in there, like a 1000 and 2000grit.
You should use a polishing compound AFTER you use a rubbing compound (as those tend to haze surfaces) the polishing comound will remove finer scratches and haze. Then wax and buff