MMKK,
As others said, pump more often will stimulate/generate more milk. Also, if you can pump during night time, will help to generate more milk as well. You try to drink more following soup can help as well:
octopus and peanuts chicken soup
fish tail soup with papaya and "honey-jo"
pork knuckle soup with bei qi and tong cao (tong cao helps improve milk flow)
Really sorry I can't type Chinese, and hope you understand what I meant. Add Oil!!