LO is mainly breastfed, but we supplemented with formula in the beginning and every now and then I mix some in with her breastmilk. She will only drink Enfamil Gentleease. or Enfamil newborn premixed liquid. Any other powdered formula she hates and gets very very gassy. We have lots of similac and regular enfamil unopened that LO will never use. What formula does your baby like?