Pumped breastmilk and cluster feeding

res932

I posted something similar below but wanted to reclarify. I pump breastmilk for DS and then feed with a bottle. Every evening usually from around 430 to 930 he will get fussy and act like he wants to eat constantly. I have him on an eating every 4 hours schedule, but should I be feeding him more often during this fussy time? Everything I can find on the topic of cluster feeding seems to relate to babies who actually nurse, not ones to eat breastmilk from a bottle.

LO eats 4 ounces at the 4 hour feedings, but last weekend we were trying to just feed him when he is hungry and he was eating about 4 ounces every 3 hours...but then ended up bloated and screaming in pain. I'd like to extend his night sleeping, but I am afraid that if he gets used to eating every 2 hours he will want to do it at night too. 

TIA!!