M.M.
There are no restrictions on bringing breast milk on the plane as long as it is for your daughter's consumption- does not even have to conform to the 4 oz rule. this also applies to formula, baby food and juices for a child. We have flown several times and have been through this with airport security- you do have to declare the breast milk, milk, formula- whatever to security as you are going through an they may do extra screening- we have taken a cooler with the gel packs- the dry ice may be an issue because it is more chemically-
For better information and the clearer guidelines go the the TSA website
http://www.tsa.gov/travelers/airtravel/children/formula.shtm
You can get ice once you get through security if nothing else and can get some on the plane.
We flew to Australia and the return trip was the same rules as leaving the US- TSA sets the rules not the airline...