Newborn 18days old..low breastmilk,are there still chances to improve my supply or shall i giv up..?

Struggling hard to improve my milk supply..want to breastfeed my baby but have to switch to cow's milk,coz she is still hungry even if i feed mine.. Very embarassed and upset,guilty feeling! Mommies please suggest ways to improve breastmilk,dont want to starve my baby..