I too don’t use aptamil but another anti reflux formula and we use the Nuby Rapid Cool for on the go bottles x
"Hot shot" method. Put your powder in the bottle ready then take a small flask to put boiling water in & shake to kill bacteria (around 60ml/2oz for a 210ml feed) then fill to required amount with cool boiled water. I usually pour boiled water into container the evening before if I know I'm out the next day, or first thing in the morning so it can cool in time 😊
Could you use the Nuby rapid cool for when you are out? Make them on the go?
I don’t use Aptamil but I do use another anti-reflux formula. I’ve been able to make bottle in advance without an issue even tho it does get thicker, but when I’ve warmed it up it did become thinner again. I’m not sure if it will be the same since being different brands but you can also give it a try xx