Should I pump one side or both sides of my breasts during midnight if my baby only nurse one side of my breast?

When my baby was smaller, I pumped both sides of my breasts during midnight if he only nurse one side. Because i felt that the breast (the side he nursed) was still full. I also read that emptying the breasts will increase milk supply. Subsequently when he was older and he drank more, i would only pump one side if he nursed the other side only. And when he started solids, the milk supply dropped and his demand dropped. He woke up to nurse one side and I stopped pumping as the breast is not that engored any more.