Bottle Feeding?

Baby (2.5 months old, eats roughly every 2.5-3 hours) is EBF, and I prepare bottles every now and then for times when I’m going to be gone and need someone else to feed him.

I’ve been told I should pump for each feeding that baby misses. Is this true? If so...could you tell me your pumping routine when you’re away from baby, even for only one/two feedings?

I don’t want my supply to suffer but I don’t want to overproduce either. 🙈 And I don’t know how much I should pump while away...

Empty the breast? Just enough to relieve pressure? Does it matter? AHH. Just looking for a simple explanation for pumping that doesn’t shoot my anxiety through the roof!