My boss is totally fine with me missing as much as I need to for this.

Look it is not easy for a person to stay at the hosipital when their partner is there for whatever reason. At some point you gotta go home and take care of yourself too. But you didn't do that. You went nack to work when have an understanding boss who is happy to give you time off work. This incident happened only a few days ago!! A few days!!

Your gf is in tremendous physical pain. She could have died and lost her pregnancy too. Stay with her dude! You're lucky to have such an understanding boss! It isn't just narcotics making her cry. She (and you too) is going to need a lot of time recover from this. YTA!