Girls, good evening, my nerves are at their limit... every feeding is the…

Girls, good evening, my nerves are at their limit... every feeding is the same, the son sucks a little, throws it off and again seeks and so on, all feeding, moreover he throws it off, I thought there was no milk, I try to express and from the breast sprays, even a little bit, but there is. God, I don't know what to do, I think he's not getting enough to eat.