I would go with the 5oz. I think it's pretty rare for bf babies to take more than 5 oz per feed, 1oz per hour is about average. I would just have a talk with daycare/ provide literature about 'paced bottle feeding' and insist that they practice it with your lo because it's really easy for care providers who aren't paying attention to overfeed a bf baby.
The main reason I would go with the 5oz is to influence caregiver perception. If they get 5oz bottles and see themselves feeding a full/mostly full bottle, they're less likely to incorrectly perceive your lo as hungry when (s)he is actually full because they'll feel like they've fed the baby more than if they're feeding an empty-looking 9oz bottle with 3oz of milk in it. They'll wait for another hunger signal rather than just believing the child "must" still be hungry, especially if they're used to feeding large formula volumes.
The secondary reason is that sending 5oz bottles would make it more difficult for them to try to overfeed the baby to make them go longer between feeds to give themselves less work to do, especially if you're sending empty bottles and they're filling the bottles themselves.
He was good with the Breastflow bottles that an LC recommended. I tried both nipples without noticing that they were different stages, haha.
