Very few mothers can't or shouldn't breast feed. Most drugs do not get to the baby in large enough amounts to prevent breast feeding. Be sure you let your baby's doctor know ALL medicines, herbs or other drugs that you are taking . If only one breast has had surgery or radiation, the other should be able to produce enough milk for your baby. I can't or don't wish to breast feed.
Babies can and do develop normally when fed only formula.
Although encouraged, breast feeding is a personal choice. You and your baby can still benefit from close skin to skin contact. The breasts contain many glands which make milk. They collect nutrients and liquid from the mother's blood and make them into milk. The milk then travels to ducts which help store the milk.