I was in the same situation a couple of years ago -- 10 weeks when we visited WDW. Take a couple of bottles of water with you each day, stay hydrated. Don't overdo it -- if you feel tired, go back to the hotel for a mid-day rest, call it a night early if you need to -- whatever you do, don't run yourself down! I also took healthy snacks in my backpack, like dried fruit, bagels, etc. because I'd often get the feeling that I had to eat, RIGHT NOW -- no time to wait until you can get to a restaurant. The snacks kept me from getting lightheaded or nauseous while in queue lines, etc.
Also, AVOID any rides that say pregnant women shouldn't ride. I talked to my doctor before I went and asked how much I really needed to follow those rules -- after all, some rides like the teacups, and even BTMRR, seem pretty tame when compared with some others. Plus, I had seen many obvoiusly pregnant women riding things like Splash Mountain. I just thought it was a question of "where do you put your belly" ... and if you're in the early stage of pregnancy and don't yet have a belly, it's not an issue, right? WRONG! What my doctor explained was that especially in the first trimester, there is the danger that the placenta can tear away from the uterus, leading to miscarriage. This can happen on any ride that involves very high speeds, sudden jerks or turns, and drops. (Hence why you can miscarry after a car accident that gives you a good bump.) So although you may see women riding who are quite clearly pregnant, don't follow their example. Play it safe ... and in the future, you can go back with your little one and do the rides you had to miss this time!
HAVE FUN -- and best wishes!!