When you do return to work, you don't have to completely wean your baby to a bottle. Nursing while working does take some planning. The more milk the baby drinks, the more you make. The missed feedings during the day can be formula or breast milk. Breast milk can be stored in the refrigerator for 48 hours and in the freezer for 2 weeks.
Some women pump while at work for the next day's feeding.
Other women find it is easy to pump their breasts in the morning when they are full. Your body will provide enough for the stored feeding and for the baby's breakfast. The milk production is very adaptable. Soon your body will be used to the missed feedings, and your breasts will not be full during the day. You can combine work and breast-feeding.