I think every women's body is different. And I wouldn't be surprised by something like getting your period too early. I got mine about 2 months after having my daughter. The first one was a little short (days) but then they got regular after that. It was perfectly normal for M. I guess. I wouldn't fret about that.
As for not being able to get pregnant while breast feeding. I'm not a doctor but I will say I believe its pure myth. And so would my best friend who is due in September who was 4 months pregnant before she found out because she hadn't had her period yet AND was breast feeding her daughter. The kids will be 11 months apart in age.
On the flip side, I'll say it again, all women are different. I also know a mom who has 5 kids and who has never used birth control a day in her life. You may say, "well that's why she has five kids", but each one was planned and so was the timing between them. She swears she uses breast feeding as her means of birth control. She breast fed one till they were ready to have the next.
Who knows what is correct really but I think the only way to make sure you don't have another kiddo unexpectedly is to find a birth control method thats right for you now. I was able to go back on the pill shortly after having my daughter. That was what was right for M..
Good luck!
J.
http://www.mommysjoy.com