Re: suggestions for building supply........
The fact that your first LO gained slow and wasn't a big eater did not preserve your milk supply nor enable you to keep up with him for a year. Nor does the fact that your second LO is gaining faster and is a big eater mean that you're going to run low on milk. Milk supply is created and maintained by demand, and all babies will be able to maintain an adequate supply for their needs provided they are allowed to nurse on demand.
Have you started pumping yet? If not, try starting by pumping once a day, after your first morning feeding, and see how much you get. If it's a couple of oz, then you're well on your way to building a stash that's going to be sufficient for the first day back at work. Remember, a baby needs only around 1.5 oz per hour of separation from mom, regardless of his size! If you don't get much, then start by consistently pumping at the same time of day and see if you get an increase after a few days. And if that still isn't getting you the milk you need, add in more pump times.
The only thing that I'd worry a bit about is your job set-up. People who teach school tend to have a hard time finding pumping time- after all, what are they going to do, leave a classroom of children who need their attention just because they need to pump? You might want to think about getting a hands-free set-up and car adapter so that you can pump on the way to and from work, in addition to your single pump opportunity during the workday.
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!"