Decreasing breast milk supply

Hi mummies, I'm exclusively pumping for my newborn and I noticed that lately the supply ha been decreasing. I used to have 90ml from both sides (in my third week post natal now), and now sometimes I only get 60ml from both sides. I drink at least 2L of water and longan red date tea a day and I sleep at least 6 hours. Not sure why my milk is decreasing? There are no clogged ducts also. I have been drinking green papaya soup, eating fish, lactation cookies etc but still the same 60ml yield. :( anyone with the same problem? How to increase the supply again? For personal reasons, I'm not able to latch the baby directly.