2 weeks newborn dips in soiled diapers and constipate for a day. What should I do?

Hi mummies! My newborn is 2 weeks old and these two days her frequency of soiled diapers is getting lesser (from more than 8 times to less than 3 times a day) and today she hasn't poo yet, only wet diapers. I'm getting concern, not sure if it is my fm & bm ratio? What should I do mums? (Her diet is mostly on fm and sometimes expressed bm/latch on)#firsttimemom #pleasehelp