Sis, I've done this a few times with PAL and honestly ang best approach is to call their customer service directly kasi the rules can be strict about liquids in carry-on, but breastmilk usually falls under medical/essential items if you explain properly at the counter, a few of us tried packing it in a small cooler bag with ice packs and declaring it right away, and they let us through, pero it really depends on which staff you get. I'd suggest bringing a copy of your booking and a note explaining you're a nursing mom, then arrive early para may time mag-explain ng maayos without rushing the line.