Breastfeeding help!!

Baby girl is five days old, and is on the tiny side being 6 lbs 3 ounces at birth, gestation of 40 weeks. She sleeps a lot more than she eats and my boobs are killing me! How do i lower my milk supply? It comes out too fast and too much for her, we both have started getting soaked during feedings. I’ve been pumping to relieve the pressure, but was told that would only increase my supply. If I stop pumping and suffer for a couple days/ weeks, will my boobs conform to how much baby is intaking?