I realize that ww says you can start then but I've never seen the okay to diet to lose weight by a credible breastfeeding resource. If there is one, please post it. You should eat well, lots of fresh stuff, fiber, proteins, tons of water. My midwives and lactation consultant wouldn't want an EBF mom dieting at 6 weeks pp. But, the op isn't nursing.
ETA: my goto source, kellymom.com, says not to diet until at least 2 moths, preferably longer. And to remember that nursing uses 350500 cals, so most women can't go under 1800/day.