questions about AF post pregnancy

ok, so I'm totally confused about my period after having DD in December. Here's what's going on with me. I bled for 3 weeks PP (heavy the first 1-2 days, the pretty light thereafter) At 6 weeks, I got what I thought was my period. I had all my AF symptoms leading up to it, and then it came. My OB said it was unlikely my period, but on the ultrasound my uterine lining was thick so he said it was possible that I was one of the rare few who get AF right after. (I am exclusively BF) He said if it came again exactly 4 weeks later, it was probably AF. Exactly 4 weeks later, I get it again. Then, 3 weeks and 2 days later, I get it again. I spoke with the nurse, and she said it sounded like an early period and was no big deal if it only happened once, but to call if it happened again the next month. So, this month, it's been 4 weeks 3 days and no AF at all. I'm not on birth control (we PNP) so I thought I might be pregnant. I took 3 tests, and they were all negative. Has this happened to anyone? I'm totally confused.

Re: questions about AF post pregnancy

It takes awhile for your body to regulate your periods again. Especially if you are breast feeding, you may not see AF again for awhile