Re: More milk with 2nd letdown?
I wouldn't read too much into the experience you just had with the pump. The way pumps remove milk from the breast can be very different from the way babies do; babies are generally faster and more efficient at emptying the breast than even the best pump. The excellent news is that you got 3 oz from pumping, which suggests that your supply is where it should be, and you probably can drop those supplements. Maybe go down to 1 oz for those 3 supplemental bottles, and see what happens.
Fussiness and hand-gnawing... Well, they don't necessarily mean anything, either. They're kind of par for the course with babies around this age- they're trying to figure out how to maximize the amount of milk they get at the breast, how to control the flow, how to self-soothe with their hands but not suck on their hands when they're hungry... It's a lot for a new little brain to master, and it can make for some very fussy days! The best thing to do is to just nurse, nurse, nurse, giving the baby the maximum number of opportunities to learn how to nurse most effectively.
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!"