Hi guys

So I stopped breastfeeding because of pain and not producing enough weight because baby is losing too much weight. So I started trying to pump while giving baby formula. I tried pumping every 3-4 hours today 20 min each. I got 3 1/2 oz from my milk building overnight. But throughout the day I got nothing or only 1 oz total. Why is my milk doing this? My breast and my nipples hurt really bad. I also get pain from the pump like its pulling too hard but its on the lowest setting. What should I do should I just quit trying to pump? I now see why she was losing so much weight because my milk isnt consistant. Help!