more sanding before buffing, the surface still looks pretty rough. Like Phelan said, no big jumps. 220,320/400,600,800,1000,1500,2000,2500. The finer each paper gets, the longer it will take to remove the previous paper's scratches too.
Did you buy an orbital buffer? Or rotary? Orbital's just don't cut very fast. Good for newbs because you can burn anything with it, but slow going so its even more important that you're final sanding is super fine. Like Phelan said 2500 or 3k would be awesome! Go buy some "pro grade" compound. 3m, novus(semi pro). They just cut better than auto parts store off the shelf stuff.