LO Constipation

Hi Mummies, Im trying to introduce formula to my 16 weeks LO as going to infant care soon. Fed her 30ml of NAN yesterday and today she did not poop at all. previously she used to poop at least twice a day on full EBM. Is this normal or is she having constipation due to the formula? Should we try other formula? Thanks for advise! #1stimemom #pleasehelp