I know how you're feeling (really, I delivered on 9/30), however there are a number of reasons why you should not diet right now.
#1: if you diet while breastfeeding, your body releases a chemical (which is then in your breastmilk) that is not good for the baby. If you decide to go ahead and diet, then you need to stop breastfeeding. Seriously.
#2: If you start to lose weight too soon after pregnancy, you may find that you lose body fat in the "wrong places". I have a friend who lost her baby weight soon after delivering (her son was in NICU and her weight loss was triggered due to the stress/situation); she lamented that she didn't lose it in her belly and mid section as much as losing the padding/curve of her bottom and fullness in her breasts.
#3: Toning your mid-section is not the same as dieting. You have to remember that your abdominal muscles have been blown out. You haven't had to use them for the past 10 months. So, you'll need to focus on strengthening those muscles. When your pregnant, your body let's you relax--basically, you've had 10 months of letting your tummy hung out. You now have to start holding your abdominal muscles/stomach in when you walk/stand/sit, as well as doing kagel exercises and crunches. That will get your mid-section looking more like you want.
#4: your body is still adjusting it's hormone levels and restarting certain processes that were put on hold while you were pregnant. Dieting during this readjustment could make that transition more stressful in your body and hormone production.
I know it's not how you want to look, but as long as you avoid eating fast-food/processed foods, sweets and avoid alcohol, you body will lose the weight even if you are eating a robust diet with dairy fat and protein for your breastmilk quality. It took you 10 months to gain your baby weight; give yourself at least 8-10 months to lose it naturally. When I first asked my OB when I should focus on losing the baby weigh, she told me "No dieting for 1 year. If after 1year, you're not where you want to be, then you can focus on weight lose, etc."
Here's a few good links & articles:
http://www.livestrong.com/article/104712-fast-lose-baby-fat/#
http://www.essortment.com/all/postpartumweig_rwvc.htm
Good luck. Try to savor the time with your newborn instead of worrying about your weight. This itty-bitty baby stage goes by so quickly!