The white on white issue is one of the reasons why I press my seams open. At least all things are equal that way.
Sometimes a white batting actually makes the issue worse and you want to go with a more off-white. Try both and see what you like/how the fabrics react.
I find once I have something quilted down and I put it away for awhile, I'm always much happier with the project than I was with it 6" from my face. And I think your project is lovely!