Dry diaper for 7-8hrs ?! 😭

My LO is about to hit 6 months on a few days. I’ve already spoke to our pediatrician about this but this is the 3rd time (not in a row) that’s she’s gone 7-8 hrs without any pee. She went down at about 9pm but nursed to sleep. We give a small feed around 11om-12am and then another around 3am. Tonight during her 11pm, I had to give formula bc I didn’t pump in time and she only drank 30ml and then rejected it. I made sure to give her BM for her next feed at 3am. When I checked her diaper before her bottle, it was BONE dry. This happened 2times last week. And I’m scared because it’s not normal and the doctor didn’t address it. We have a follow up appointment soon and I’m going to speak to them about it again of course.

Anyone else experience this ? Was it dehydration?