Infant Multivitamins

So I recently read that breastmilk doesnt provide all the nutrients a baby needs. It lacks iron and vitamin D. My baby is 9 weeks old now. We have been mostly breastfeeding but supplementing with formula 2x a day. Now Im worried he isnt getting what he needs. For those of you who formula and breast fed, did you give your baby supplements too?

The pediatrician never mentioned giving him vitamins before in person, but I just read the sheet they send home with us and it says all breastfed babies should take vitamins.