I know when I traveled with my baby, I could take my pumped milk onto the plane with me, because baby food items are an exception to the rule. However, I don't know if they would still let you since you are not traveling with him. I agree with the first poster and I would call the airline just to be safe. I know exactly what you mean about your milk being like gold to you, so I think it would be better to wait on hold forever to know for sure then to get there and have to dump it.
Also, how long is your flight? Could you pack a smaller cooler with tons of ice packs and pack that in your checked luggage? Even if you don't plan to freeze it, you can fit more milk in a cooler if you put it in those breast milk freezer bags rather than the pumping bottles since they can be squished around. We traveled a lot by car when my daughter was bfing, so I did that quite often if I had more than what would fit in bottles. I could fit several of the cold, not frozen, of the Lansinoh freezer bags (my personal fav) in this Playtex cooler http://www.toysrus.com/product/index.jsp?productId=258566...
It keeps things cold for a long time, so I'm sure it would keep your milk cold if you had a long day of traveling. You stick the entire bag in the freezer and the freeze packs are built in the cooler.
I have also heard of several moms shipping their milk home while they were away, so you could always try that, too. I have never done it, so I don't know exactly how they did it, but if you could find out how they kept it cold long enough, you could do that or you could use the same technique to store it in your checked luggage and it would stay cold for your trip.
Good luck with it!!