Baby on breastfeeding should pass urine atleast 5 to 8 times a day. If she is passing lesser, please try to feed her on demand and also in the night times (atleast twice). Just check in her genitalia whether there is any redness or diaper rash, is she left in wet diaper for a long time?. If she is active, playing and gaining weight, not to worry. Or else you need to check with your pediatrician, if this persists