Your milk won't come in immediately after birth but only the colostrum which is the first milk that comes out (thick yellowish in colour). It may take days for your milk to come. Just keep latching your baby. Your baby's stomach during the first few days of birth is very small and only needs a few mls of milk to feel full. You also don't need to pump UNLESS your baby is born premature. There will be lactation nurses around to help you with manually hand expressing your colostrum and you can also ask her to help you measure your nipples so you can buy the right flange for your breast pump to pump at home.