I'm an exclusive pumping mum. Currently taking fenugreek to boost supply and lethicin to prevent clogged milk ducts. For the first 1-2 months I do power pumping quite frequently. Note that yield does vary throughout the day and on different days as well that's normal. But I notice overtime the supply will increase gradually I started from 20-30ml each side to now around 40-80ml each side, with reduced pumping sessions as time goes by.
Keep hydrated. Power pump. Find your milk booster - green papaya fish soup, oatmeal, lactation cookies, to name a few. Not everyone respond the same to milk boosters though. My supply regulates well with baby's intake - not a single drop extra >< and most of the milk boosters failed me (even supplements from gynae). I did try supplements from Legendairy too
You may find this article helpful https://kellymom.com/hot-topics/low-supply/