I just flew with my 18 month old and had 3 8 oz bottles of milk with me and no problem at JFK in NY or MCO, they did open it and test it but that was it.
-Michelle
We had a similar experience in Dulles and Houston - you should be fine. The doctors note certainly can't hurt, though. I know some PPs were suggesting to limit what you bring, but honestly - I'd overestimate. Flights get delayed and cancelled all the time. 10 hours can pretty easily turn into 14 or more, and being on a plane with a toddler who doesn't have their usual comfort food or drink is a very unpleasant experience for all involved (as me how I know...
