Father needs help

We have a one month old baby and what a joy he is! He still hasn’t gained back his birth weight, and my wife is trying her best to breast feed, but sometimes, he just won’t latch and is just crying and crying. I think I made a mistake just now because I took a bottle of pumped breast milk, and gave it to him. (Less than 2oz) He immediately took it. She got really upset and cried in the bathroom saying that she “couldn’t wait for me to go back to work”… (military on paternity leave). She has come down from the rage now. She is still working on the supply, but we’ve basically been told that we need to supplement with formula. Did I do the right thing? It’s easy for me to sit back and say “just give him formula,” but I know, after our previous two children, that it’s not ideal. She’s not pumping out a lot of milk, although it’s usually after feeding. She keeps talking to herself when he’s trying to latch, getting stressed out about the situation… I just wanted him to eat. How could I have done it better? I brought her the pump when I gave him the bottle, but I think he got the boob after anyway.