Iron supplements after 6 months of child birth is recommended if you are diagnosed to have iron deficiency anemia. Iron in breast milk is enough for a baby.
Calcium is maintained in your blood and breast milk, the need is, Vit D level should be in the normal range, if not then it's enough to take only Vit D supplement, there is lot calcium in our food to get absorbed from your gut, in the presence of Vit D.
For infants we should give daily Vit D drops since birth, to fulfill their daily requirement for their calcium metabolism. You can connect online to clear your doubts about nourishment and supplements.