Hi.
I appreciate your concern for your baby.
Relax do not worry,your child is gaining weight,
anxiety will interfere with milk production.
BREAST MILK IS THE BEST MILK ,so should not supplement with any other milk.
watch activity of your baby,watch for his urine output.
I suggest you to take good nutritious diet,have plenty of fluids,fruit juices,milk,
Your baby will be fine.
God bless