It is possible to have an oversupply of milk.
It is important to breastfeed a child till 1 year. It is not advisable to give formula milk before the age of 1 year.
Do not worry about this as it will only make this problem worse.
New mothers might worry about breast engorgement but there is nothing to worry about much.
It is very rare that mothers have to deal with less breastmilk production. Nevertheless, there are always ways to deal with it.