Wait a couple of months until your milk supply is established. I've personally been having some supply problems and my baby is 11 months old. I've never had them before with my first two, but since I've been "seriously" starting to calorie count and eat healthy the last couple of months, if I eat too few calories I can tell my breasts are saggy/dry and not full (I'm talking like 1500 calories here! I HAVE to eat at least ~1900 calories + lotsa water to maintain adequate supply). If this had happened when the baby was much smaller it would have been a serious problem.
So I'd suggest be easy on yourself. (One book I read called "The Girlfriends Guide to Pregnancy" by Vicki Iovine-one of my favoritest books, suggested the 9 months on, 9 months off plan. IOW give yourself at least 9 months to relax and enjoy the amazing thing your body just accomplished, and don't worry about your weight except on a slow and gradual process).
And make sure you're getting HEALTHY nutritious calories. Your body just went through a lot, give it the right "tools" to get strong again