weight gain already???

I am technically obese and shouldn't gain more that 11-15 pounds this pregnancy, and none the first trimester. I have been carefully measuring, weighing, and tracking my food and getting exercise. But I have gained a pound in a week! I'm not supposed to gain more than 0.5 pounds a week, and that is later in pregnancy! I know there is a lot of bloat going on but this is so discouraging!