Breast milk??

So my baby is 3 days old and my milk is coming out super super slow and thick. Its still colostrum. But my baby gets mad that he has to work hard for it. If I pump for 15 minutes i won't even get close to half an oz. When will real milk come out or when will it come out faster and in more amounts. My baby is hungry and I can't help him. I end up having to give him formula in a bottle because I can't give him enough. Any tips to make more come out ?