Pumping on one or both breasts?

In 4 weeks I will be heading back to work (only 2 days a week) and trying to figure out my pumping schedule, however I still want to breastfeed as much as possible. When my son is nursing I do not switch sides but I do alternate breasts at each feeding. Since I am not having him eat off both sides during each feeding should I be pumping both sides every time I pump? Or should I only pump one at a time and alternate like I would while nursing? I have a pretty good supply of milk and I’m worried about getting engorged if I start pumping too much