Baby didnt pooped for 3 days

LilBarbieFeet
Hi mommys my baby boy is almost 3weeks old and since 3 days Im trying to transitioning from bottle to breast. I was breast feeding my little one during the day and only during the jight gave him formular. Now since than he didnt pooped. He is farting a lot not really showing that he is unconfortable and he has a lot of wet dipers. 
Before that he was pooping every day when he was eating more formular. 
Should I be worried or is that kinda normal? I red that some babies on breastmilk dont poop up to 10daya and some say they poop every day. Argh .... Any advice here??