D.C.
Hi K.,
I nursed my daughter until she was almost 2. I had to travel for work during the first year, and I was fortunate to have enough milk stored up in the freezer before I left so I didn't have to supplement with formula. I was more concerned about maintaining my supply while I was gone, so I made sure to pump every 3 hours (except while I was on the airplane).
If you have enough time before your trip, can you work in an extra pumping session (preferably early in the morning) so you can store up some extra before you go?
Here's the link to the TSA website regarding breast milk.
http://www.tsa.gov/travelers/airtravel/children/index.sht...
You are permitted to bring it on the airplane with you. Like the other poster below, the TSA had more questions for me on the pump than they did with the breastmilk. I would recommend pulling out the pump and putting it in a bin, just like you would with a laptop. On the way home, declare to the screener that you have breastmilk before you go through security. They may swab the pump with that explosives detector thing, but they never made me dump out any milk.
I was fortunate that I had a minifridge in my hotel room, and there was a freezer at the work location I was going to. I always froze the milk (using the freezer in the hotel room, or preferably the full size freezer at the office) figuring it was less likely to spoil if it was frozen rather than just refrigerated. You may want to bring extra gallon size Ziploc bags to keep the milk in so there's a double layer between your milk and the freezer. You can also use them to put ice in to keep the milk cold while you're on the airplane, and you won't have to worry about leaky ice. I was usually able to refill the ice just before getting on the airplane from one of the restaurants near the gate area. I always carried the milk on with me; if your flight is delayed, you can make sure to get extra ice. You won't be able to do that if it's in your checked luggage.
You may also want to call ahead to the office in NYC to see if they have a designated pumping area and a freezer for you. I did that when I had to go somewhere, and they set me up with a special locked office and a freezer I could use. You'd be surprised at how accomodating some people can be if you just let them know what you need.
My daughter maxed out at 6 oz of breastmilk per feeding. She's never been a big eater.
If you really don't think you'll have enough milk, you should make sure they have some formula if the milk runs out. A little bit won't hurt her. It's going to be OK!