You may want to see a lactation consultant. There's a tool called inverted nipple corrector, lactation consultants maybe able to advise and help you. I used to pump 3hourly, 20-30mins each time. During the early weeks only yield 30ml. If pumpsing session coincides with feeding time, I'd just pump for 15mins after latching. It's demand and supply, your supply will regulate according to baby's needs. You can try power pumping to increase supply. Try milk boosters, but it does not work for everyone. Keep hydrated and dont be stress
Mommy i joined a group of fellow breastfeeding moms. They advised to better start pumping at 6th week coz early pumping may result to over supply. To increase milk supply you need to direct latch and drink plenty of water, but since you have inverted nipple you had to see a lactation consultant to learn on your LO's correct way to latch.
JSB Hema