Hello! I've had a mirena implant 4 years, with no periods since winter of 2012. I had it removed August 11, and had my first AF September 13-16. I'm still trying to figure out this app and my cycle. Glow estimates my ovulation as today, but according to cm and cer posit, I'm not quite there. Has anyone else experienced this difference? And as you log more months, does it hash itself out? I don't want to get too overstressed about it since we're just starting out and having fun, but I still want to be informed. Thanks!