If the lactation cookies or supplement don't work for you, try to stop taking those since the effect of these really vary. For me lactation cookies even decrease my supply further.
Power pumping is the only reliable way to build up supply. You pump for 20 minutes, rest for 10, then pump for 10, rest for 10, then pump for 10 again, so 1 hour total. Do it once a day for about a week and you should see result. Good luck!