Yeah Doctors don’t know shit. I’ve personally teached dozens of Doctors and they are complete morons and what people, especially parents, should do changes every few years. Listen to your gut and your babys. It knows when it needs to eat. You only have to keep track that it eats enough and this you can do with a scale. Weigh your new born every few days to see if it gains weight. Don’t forget, some loose a little weight in the first weeks before they start gaining.