Girls, hello! Can you tell me who had what weight gain in the first month?

Girls, hello! Can you tell me who had what weight gain in the first month? We went to see the pediatrician today and the weight gain was 400 grams, the nurse said it's little, the doctor said it's normal. I asked my acquaintances, some say it's normal, some say it's little ( And what should I do so that the baby gains weight normally? We have mixed feeding, breastfeeding and after feeding we give formula because it seemed like the baby wasn't eating enough breast milk.