i am no expert on this. not even close. but i can't help wondering if you need to add some basting to the sandwich. don't we get lumps and bunches because the top and bottom are moving around in different directions to each other, or because they aren't feeding at the same rate?
how lumpy/bumpy is your machine bed? i tape a piece of manila folder and one layer of freezer paper to mine. nowhere near as good as i think one of those silicon mats would be, but it helps me move the quilt around more easily.
AND i'll bet you dimes to donuts it looks better to everyone else than it does to you. :wink: