So I am losing a lot of trust in my sons father (sperm donor) and that side of the family. My baby is breastfed exclusively and when my son goes over to their house(max of 3 hours) I pack a 4 oz bottle of breastmilk to go with him in case he gets hungry. I feed him before he goes and that's probably why he drinks a little to nothing in the three hours he's away from me, but I'm still weary. What are signs to look for if they fed him formula? My suspicions come from Christmas Day when he went over there for 4 hours and I packed a 4 oz and 2 oz bottle of breastmilk and he drank nothing and didn't poop for 24 hours after. He is an every 2-3 hour eater even at 5 months old. My son went over there on Friday for 2 hours and drank nothing and now has not pooped all day today. I'm concerned and getting really skeptical and pissed  about them going behind my back and feeding my solely breastfed baby, formula. I provided breastmilk and I expect you to use that. Why would someone do that? 

Sorry for the lengthy post