Could be worth trying an open cup/sippy cup/straw cup? Hopefully you can find something he likes to drink out of and can give him expressed milk from that instead, doesn't have to be a bottle 😊 good luck! 🤞
I'm in a similar situation. Mine has managed to do 1.5oz from a bottle 3 times but it takes a really long time and he often is just chomping. I'm going to buy a sippy cup, I have a tiny open cup but I think it's too messy for now, even though it says 4+ months
Following as I’m in exact same situation tried everything and Ive hit a wall with it