Hello and welcome to HCM,
Since. your's birth weight
was low, supplements are required for quick recovery of the weight.
As you have mentioned that your baby is on formula feed, there is nothing to worry.
The formula feeds has nutrients is correct balance as per baby's requirement.
Breast milk is best for the baby, however if the baby is not taking your milk you can continue on the formula feeds.
Weaning (giving food other than milk) can be started after six months.
This includes rice-dal, daliya, soups, coconut water, mashed potatoes, etc.
Right now (your baby is only three months old) only milk should be given.
Thanks and take care.
Dr Shailja P Wahal