Yes, tons of exclusively pumping moms are able to supply all of their baby's needs with pumped breast milk. Breastfeeding is a perfect supply-and-demand relationship and to keep it up, self-discipline is the key. If your breasts are drained completely and often, your body will continue to produce more milk. Pumping or breastfeeding often (every two to three hours) is especially important in baby’s first few weeks of life, so that your milk supply is well established.
Pumping moms use several techniques to help boost and keep up their pumping output. First, you'll need a great pump. Hospital-grade is best (and pricey), but professional-grade double electric pumps are great too. Try massaging your breasts before and during pumping, and make an effort to be relaxed. If possible, look at your baby (or his picture) while you pump — just the thought of him can make for a stronger milk ejection reflex. If you have trouble with your milk supply, get hands-on help, and talk to a doctor or lactation consultant about herbs or other drugs that can help boost your supply. Here are some other tips for getting more milk when you pump.