Breastfeeding

I want to try breastfeeding (this is going to be my first child) and of course everyone is aware of the benefits of doing so. I know this sounds selfish, but I don't want my boobs to get saggy. On the plus side, I've heard breastfeeding will make you lose the pregnancy weight faster. Any truth to both of these from experienced breast feeders? Did it make you saggy, or did it make your body better/slimmer faster?