Hi; hope you are feeling much better. One suggestion I have about bags is to consider a non-rolling bag and a separate luggage cart. I love Red Oxx's XS Aviator bag. It's 15 x 11 x 8 inches of pure packing space. I have one and it holds A LOT! I also have a Samsonite luggage cart and it is very light weight and folds quite small. You could stash the folded cart in the overhead easily with one hand and put the XS Aviator underseat. Any underseat bag with wheels and a handle is going to have less packing space. This way, you get more packing space and still roll your bag.
http://www.redoxx.com/extra-small-av...011-xs/product