Girls, I need advice. Giving the baby breast milk for one feeding empties…

Girls, I need advice. Giving the baby breast milk for one feeding empties one breast. The second one remains, so I have to express it to prevent stagnation. After waking up, I give the opposite breast that was expressed. That is, alternating. And so in turn. Now I'm thinking about how constantly expressing will make more milk come. Where can I go if she's still small and can't handle both breasts at once, falls asleep. Just with the first child, I didn't know and didn't express, then the breasts were stony, I struggled for a long time. What would you recommend?