J.W.
Dear L.,
Your baby is too young for any kind of 'food' other than breastmilk or formula. If you are worried about weight gain supplement the breastmilk by giving a bottle of formula after you nurse. However if you are nursing whenever your baby is hungry you should be producing plenty of milk. Make sure you are drinking a glass of water every time you nurse to insure you are not getting dehydrated. Talk to your pediatrician before you introduce any food.