@Shaniya thank you but unfortunately my daughter is on prescription formula for her CMPA so it’s a case of carry water or ready made up formula using her powder 😫 I should have stated sorry!
You can take empty bottles, some powdered formula in a container plus boiling water in a thermos; then you just make it up when needed. I usually portion formula out into little containers to help me and make it more fuss free x
I have these and they didn’t leak. You can also ask for hot water at the airport cafes and on board x
We had this same issue with the Dr Brown bottles and didn’t want to change the bottle. So we carried empty bottles and ready to feed formula instead and just poured out as needed (and discarded the leftover milk after an hour of opening).