Im really struggling with expressing but love breastfeeding. is it okay to supplement breastfeeding with formula feeds. how does it impact my baby?

The system: The breast is an inducible system. That means the more often you feed the more it is stimulated to make. When/ if you supplement, it removes part of the stimulus for the infant to feed and can eventually trigger a weaning. An add on supplement of an ounce or so after 5min/side may help you get over a rough patch. The final point is you must get though it. Do what you need to feed baby & thrive.