Monica, I have a friend who conceived their second child that way. She hadn't gotten her first ppaf, but was convinced she was going to ovulate soon. They charted for a few months and she got pregnant. At her first ob appointment, when asked how long since her last AF, it was something like 34 months! They couldn't believe it.
~Joan, Happy mom to 2 beautiful kiddos, one new puppy and 2 lovely felines