Dish is probably ok but bigger is always better
In concept the dish setting determines the width / flatness of your arc and motor elevation sets the position in the sky. I realize this is simplistically stating things but perhaps raising or lowering the motor elevation a hair would help. You should be able to see roughly 55 to 60 degrees from center in both directions. If you can see that wide at this point it sounds to me like maybe motor elevation.
Run the dish out to the furthest west sat you can see (have signal from) now gently push up on the dish and then pull down. Did signal change with either move? If so note which direction raised signal. Now do the east sat. If they are opposite (up in the west and down in the east or whatever) you are not perfectly centered on true south. Move the entire assembly on the pole a very small amount in the direction of raised caused the increase.
If they are the same (both raised caused an increase) raise motor elevation a hair. If both down increased signal lower motor a hair. Keep working the system this way and you will find peak signal and a nice arc.