I drink 8 cups of water a day. coffee in the morning. why do i have oliguria and bloating?

Not sure: If you have oliguria despite adequate hydration you may need further evaluation that may include laboratory and radiologic examination

Output: If you sweat a lot (usually from exercise), 9 cups of fluid a day may not be sufficient. However if you are having symptoms such as swelling , you need to consult a doctor. Are you feeling well otherwise? (Bloating is not uncommon during the latter part of pregnancy).