When should I pump?

Chelsea

Tried pumping for the first time about 30 mins after my baby ate yesterday evening. She usually eats from one boob and I alternate each feeding. I pumped from both breasts and at the next feeding, there wasnt enough. Should I only pump from the boob she has just ate from to save the other for the meal? Or maybe pump the opposite boob shes feeding from?

I'm confused lol.