L.D.
YES! The exact same thing happened to me. I lost the first 20 pounds (I only gained 30) and then kept the last ten (and even gained some more) while breastfeeding - and I breastfed A LOT!
When the baby was exclusively breastfeeding, I always wanted to eat and craved, uncontrollably, sweets. I would wake up in the middle of the night and shove chocolate chips in my mouth!
When the baby cut down to just one or two sessions a day, I still wanted to eat all the time. I ate mostly healthy food, and exercised, but still held on to those pounds. I agree with the other responses who blame the hormones and lack of sleep.
Good news - though. I weaned my son at 1 year and my daughter at 2 years. After weaning, my appetite went back to normal and I ended up at pre-baby weight (and smaller) with no effort in a very short time.
Give yourself break.