Hello everyone) I wanted to ask who on the formula you give your babie…

Hello everyone) I wanted to ask who on the formula you give your babies, we were at the pediatrician last month, weight 6,300, height 70. He's small, but the doctor said not to give formula yet. Now in five months, we will be giving it once a day, I think he hasn't gained much weight, it's not really noticeable when I hold him, he's really light. So I'm thinking of giving formula once a day. But according to his genes, the husband is also thin and tall, and I am thin too, could this affect the baby's weight?