After you give birth, you won’t be able to have so much milk supply. Usually the first few weeks mostly is colostrum, so take your time don’t be stress as that will affect your milk supply. As time goes by, your milk supply will increase. Advice - After you give birth drink more green papaya fish soup that will help. Otherwise you can get lactation biscuits etc. Don’t worry so much on milk supply first. Even if you do not have enough milk supply you can let your baby have breastmilk during the day and formula at night. First it will ensure you have enough rest. Not enough rest will affect milk supply as well. Second it will let your baby have a smooth transition to fm when one day you intend to stop breastfeeding.
Don't worry abt it, u'll only know aft baby is out if u have enough or not. The best is to constantly get baby to latch as it stimulates supply. Some moms try to take galactagogues nearing EDD, there's also Legendairy supplement called Cashcow tt u can take aft 36th wk. But it really depends on individual bodies. My colleague who took tt before giving birth had an oversupply tt she had to suffer frm a few bouts of mastitis while I battled with an undersupply in the first 2 weeks before my supply shot up.