Will breastfeeding help me lose weight?

Yes. Yes, yes and yes. Breast feeding will help your uterus shrink back to its normal size faster and will help you shed the pregnancy weight. Even though it's nice to lose weight, remember to eat healthfully while breast feeding - your nutrition is your baby's nutrition. So eat well, breast feed often, and watch yourself get smaller while your baby gets bigger.
Yes. Breastfeeding will make you a happier mom. Happy people are less likely to either overeat, or be overcritical of their own appearance. Either way, you'll like yourself more -- including how you look.