Girls! Question about breastfeeding. I feed every 2 hours, but at home…

Girls! Question about breastfeeding. I feed every 2 hours, but at home, milk comes in average... If I go out on the street or run errands, my breasts swell from milk, straight lumps form, through 2 hours. What's the trick? And second question, if they ate Nutrilac Comfort against constipation and colic, can you switch to Anti-reflux from the same manufacturer?