u/Aggravating_Let_995

I’m new to the world of pumping and all things breastmilk despite this being my second baby lol. My baby is 3.5 months old and 10 lbs a very little girl. I’ve avoided leaving the house for extended periods because I can’t for the life of me understand how to keep the milk safe. I constantly see you can’t mix milk temps so I haven’t been, when I pump at work I’ve been pumping into separate bottles and just leaving before the milk hits the four hour room temp mark. I recently bought the Momcozy breastmilk cooler….. if I can’t mix temps how do I use it? I thought I would just pump and pour into the bottles and then put in the cooler. Is it only good for two 10 oz pumps? I pump roughly 3-4 oz every 90 minutes to 2 hours, so did I just waste my money? Any advice welcomed!!