L.A.
The rule we were told is that the TSA will allow that amount of liquid that the baby can reasonably consume. When flying to the DR from NY with our then 7 month old, I took 7 8 oz bottles worth. Considering the amount of time spent in the terminal and in the transfers to and from the airport, it wasn't at all excessive. On the return trip, I put the powdered formula in each of the bottles, and carried enough water in sealed bottles to make them all up. No problems with that. If jarred food is going to pose a problem, consider taking infant mum mums, or a banana in the terminal.
Happy flying.