how to increase weight of child 7 weeks old to normal weight?

A. Now I do not know what is your range of normal weight weight what was the birth weight of your child and how much has your child gain so I must tell you first you should know that the child is meant to gain at least 500 g in a month and if your child is not gaining that with your breastfeeding then you should go ahead with formula feed along with it for better weight gain and growth