K.F.
I know it's painful to let that milk go, but you could always consider donating it locally while you are on vacation. I had an overabundant supply so I donated to an individual thru a group called milkshare dot com. There are plenty of babies out there (adopted or otherwise) whose mothers can't provide them with breastmilk but who cannot tolerate formula. You'd be doing a great service and wouldn't have to fool with getting the milk back on the plane. Most mommies are willing to come to you for it. It is probably worth checking out anyway . . . . Good luck!