Struggling to balance breastfeeding and pumping for bottles — how do people do this?

This might be a silly question, but I’m finding it really hard to figure out the logistics.

My baby is about 6 weeks old and I mostly breastfeed on demand. Right now I only give one bottle at night, but I’d like to introduce a second bottle during the day so I can get a bit of a break sometimes.

The problem is I can’t seem to figure out when to pump. Her naps are unpredictable — sometimes 30 minutes, sometimes an hour — and by the time I think about pumping she’s hungry again. If I pump too soon after a feed, I feel like there won’t be enough for her next feed.

How do people who breastfeed on demand manage to pump enough for bottles? Do you pump right after feeds, at a set time every day, or replace a feed with a pump session?

Would really appreciate hearing what worked for others because right now the timing feels impossible.