I am not currently breastfeeding, but when I was breastfeeding my first, I recall that I was starving all of the time, anyway. I ate as much as I could (it seemed I could never hold enough to really keep the hunger away) and was still losing.
In my last pregnancy (which was my first), I never really got that hungry – as a matter of fact, I found myself “forcing” myself to eat. I gained about 35 pounds, and never even really felt like I was eating that much.
Now that I’m in my second pregnancy, I am constantly hungry and always craving red meats and very protein-heavy foods. I eat so much more than I did with my first pregnancy and at 16 weeks, still have yet to gain (my pre-pregnancy weight fluctuated between 180 and 185 – at my 14-week check-up was 184.6, and today at 16 weeks when I went to review US and labs I was 183.0).
My advice would be that as long as it appears that your body is using what it’s getting, keep eating! With my last pregnancy, my iron levels ran a little low, but this pregnancy, the midwife said they are perfect. I’m certain it’s a result of giving in to the cravings for protein/iron-rich foods, so I guess my body just has a better idea of what’s needed this time.