Amount of pumped milk per feed when away; 9 month old

I’m still sending 4 oz bottles with my 9 month old baby to daycare, mostly because that's how much each pump session makes.

She's gaining weight well. Solids are mostly for fun and not calories.

At home she is breastfed on demand, but I have no idea how much she gets since it's direct breastfeeding instead of bottle.

Should she be getting 6 or 8 oz at a time? And then they can be spaced out more? The reason I ask, is someone acted surprised that her bottles were “still only 4 oz” at that age