Re: Supply and latching issues
Pumping every couple of hours with a hospital grade pump and getting just 120 ml (4 oz) per day... Hmm. Makes me think that something physical might be up that's preventing you from producing more. So in addition to the excellent recommendations above, I'd suggest getting checked out for thyroid issues (very common postpartum, even in women who never experienced them before) and talk to your doc about the possibility of a retained fragment of placenta. PCOS also might explain your difficulties, but since you seem to have had o trouble nursing your older baby it seems unlikely.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"