I have to agree with the pp. Stains are something you will learn to accept. They do tend to fade with use so don't stress too much. It is hard at first though, you have paid a lot of $$ for them, when they're new they are so soft & clean, but they are still diapers.
It sounds like you have a good wash routine. Like the pp, you can lay them in the sun on a bright day, that will help.