Today is 4 days after birth, the baby is losing weight. Almost not letting…

Today is 4 days after birth, the baby is losing weight. Almost not letting go from the chest, yesterday the whole breast was full, the son did not manage to suck everything. And at night as it happened, there was no milk, I fed on the breast from 2 hours of the night and until 5, they cried loudly. In essence, we should have been discharged today or tomorrow, but due to the weight loss and speech, it can't be. Who had this, how many days after that the baby started gaining weight? P.s. The breasts hang almost for an hour, we eat every 1-1.5 hours, maybe more often if he doesn't sleep. Milk is