How long should i pump both breast after 6 hours of working so that milk will not decrease? (baby is almost 3 months, drinks 4-5 ounces each feeding)

Long enough 2 'empty: hard to give a firm time. pump enough to get enough milk, and so that you can tell your breasts "feel less full". The more time your breast spend feeling engorged, the more signals that sends to your body to decrease milk production. It would be ideal if you could pump every 3-4 hours, that should help maintain your supply better than going 6 hours.