The best advice I ever received about free motion quilting was when you see something that is not "perfect", just keep quilting. Then when it is done, see if you can still see it....if you can then fix it ( unsew it and redo). 90% of the time, you can't even find it and most of the rest of the time....it's not that bad. Character I call it. The Amish ladies have said "only God can make something perfect." I lean on that idea.
Enjoy the effort.