It could just be stress and still having hormones out of whack. I know I have days where I just dont know if I can make it! My husband works out of town for 2 weeks at a time, and when he is gone it makes me crazier, and the kids seem so much more difficult. Im sure you will adjust. I always say that it only takes having toddlers or older kids to make a baby seem easy! Mine are 2, 4, and almost 6.
Hope you feel better! I'm sure it's a combination of both also. Can you put them in a daycare or something for a day to get some free time? I noticed also my kids are acting out more since I got preg. There 10 and 12