Actually the speeds I suggested are based on a 6.5 pad but you should still be ok. Try making your passes slowly and allow the polish to work applying some pressure.
The polish is simply breaking down and doing so quickly because of the the speed most likely. I suggest you set the speed on 3 to spread the polish evenly accross the pannel. Then move to 5 and work the polish until it breaks down completely. You should only have to remove a very thin difficult...