Breastfed babies can go weeks without doing a poo as its natural and absorbed back almost completely so often they don't have anything to poo.
Not sure about formula fed babies but they can get backed up as well.
Give some cooled boiled water after a feed and it will take several hours but should set things in motion.
She is fine. Formula feed babies don't poop everyday. After 3 days I would begin to worry
I have never heard of that. My daughter didn't poop for three days and she was fine.
All you have to do is help them. Rub her tummy in a clock wise motion, do bicycle motion with her legs,... They have some drops called baby move to help them poop. Also, get a probiotic powder and add to their bottle if you're bottle feeding. It'll help regulate their digestive system. My daughter poops every other day
i would take her in right away