With my first two pregnancies, I did not hold on to any extra weight and even dipped down below my pre-pregnancy weight while breastfeeding. I can tell you that this is not a good thing. Being underweight and breastfeeding causes all sorts of health issues as it messes with your immune system. I would get sick all the time and I developed some autoimmune stuff, too. Not good. This time I seem to be holding on to about 5 pounds, which is awesome, and it's preventing the autoimmune stuff, so far at least! FX! So, really, it is nature's way of keeping you and your baby healthy. It's the way it should be. I'm sure once nursing demands decrease some, you'll be able to lose more.