I was told BF babies might not poop as often because they use the breast milk more efficiently and may not have as much waste.
It's normal and your baby is unlikely to be constipated. It just may be uncomfortable.
Just a warning, if it's been a few days without a poop, put your baby in clothes you don't care about and wait it out. You might have a blow out poop

Up the back, down the legs, etc. You can either chuck the mess or wash it, but sometimes there are stains which is why I recommend old clothes.