Me too, OP.
I put on 3 stone during pregnancy with DC2 (only 1 stone with DC1), lost 1 stone at birth and in past 2 months since he was born have chucked on 8lbs and counting.
I'm 3 stone above my ideal weight, which I did reach for a brief moment in early 2010. Did WeightWatchers after DC1, lost weight easily and so this time I've been complacent.
Am quite
at myself, but I can't stop eating! Night feeds are the worst, I pump myself full of sugary drinks and chocolate biscuits to stay awake. I'm absolutely knackered.
I was planning to wait until after Christmas/ after bf to start a diet, but so few of my clothes fit me now, and I look so awful, I think I might have to start sooner. I still look 6 months pregnant. 
Exercise isn't really an option as I've had a prolapse and it's uncomfortable if I'm on my feet too long. I tried going out walking with the buggy a few weeks back and felt awful afterwards. GP (doctor) says I need to take it easy at first, swim or something, but no way I'm putting on a swimming cossie looking like this! I was going t the m regularly until about 35 weeks, so this all just feels spectacularly unfair. Even if I know I'm the one who over-ate.
If it's any consolation, I did WeightWatchers after finishing bf with DC1. I was only doing one feed a day by the end. But I lost something like 5lbs in the first week on WW/after bf. Am sure it would be more if going from full-time bf to diet. It was around 9 months with DC1, when I started cutting back bf'ing, that I felt like taking control again. Even so, the last 10lbs or so stuck and wouldn't budge, hence WeightWatchers.
I just know that I'm going to have to diet for the rest of my life now. My old body has gone forever.