Not pooping

Hi. My baby's 7 week old and mix feeding. Once or twice a day ay binibigyan siya ng formula pero mas madalas na breast feed siya o kaya naka-bottle na pumped bm. Now po ay 3 1/2 day na siyang hindi naka-poop. Meron po bang same case here? Katatapos niya lang din this week ng penta, pvc at rota vax. I don't know if that affects the frequency of her pooping. Based sa mga nabasa ko kasi normal for full bf babies yung medyo matagal mag-poop, pero im not sure kapag mix fed. Planning to bring her to her pedia again this week if hindi pa rin sya makapoop tomorrow. Huhu.