I'm using the 12x12x8 and the flat rate boxes, and I've noticed that I can fit 18-20 eggs in the boxes. Am I packing them wrong?? The person who suggested I used the 12x12x8 said that usually you can only fit 16 eggs in there, and these are standard size eggs. They end up being in 2 layers, with a little room for movement so they're not packed too tight. Are they not supposed to be put on top of each other??? Each egg is individually bubble wrapped, and large bubble bubblewrap is lining the box.