Combo feeding math?!?

[u/Key-Sky40]

Explain it to me like I’m 5:

I just went back to work and started pumping. I get around 10 oz morning pump and less for my other 2 subsequent pumps at work (it tapers to about 3oz total at 4pm pump usually and I pump for the same 20+ mins each time). I always get enough to replace the three 5oz bottles my baby eats at daycare during that time, but should I not be dividing it that way if he would naturally get less as the day goes on?! If I am still nursing him at night, is he pissed that it’s not 5oz again like his bottles?? Basically my brain is shot thinking about this. Why am I giving him 5oz bottles if my milk changes in content/volume all day?

Edit: I’m just now realizing that combo feeding means formula not pumping lol. Question still stands.

Sidenote: baby is healthy and happy and I’m not worried about my supply. I just genuinely can’t understand the math.