Breastfeed & Poop

Hello Moms -- I have a 4 week old daughter and wanted to understand how often does your Lo poops, she is exclusive BF but in night once I give her formula as Sometimes I hardly get enough milk. Also she only poops once a day or once in 2 days, I'm a bit concerned as she gets really fussy and cries if she doesn't poop. Also she has got small acne all over body is it normal? I showed ped and they said its baby acne but it's increasing