I had my first period at 4 months-and I was exclusively nursing. That really irritated me. I felt like I had just stopped bleeding from the birth, was I ever going to stop bleeding? They were regular from that point on, although I had an IUD a month after that first one, so that probably contributed to it. DS wasn't a big nighttime nurser-some nights every 1/2 hour, some nights not for 4 hours. Played hell with my hormones. It's kind of hard for me to sympathize, I wish I had been lucky enough to have 10 months. I never used bfing as birth control, though. Too much conflicting info from trusted sources. I didn't feel comfortable being that rare woman that exclusively bf's and still gets pg at 4mo!