Ovulating on CD 36?!

AJ
Hello! I am 7 months pp. I have had seemingly regular cycles since about two months Pp. I am currently BFing. I have been expecting AF and it is pretty late. I am now on cd 37. I had all signs of ovulation, so I took a opk and it came back positive?!? How is that possible?!?! I also took an hpt that was negative. Thanks