This is my second month using Glow. This month I decided to use opk's for the first time. I did one yesterday on the first day of my fertile window (as predicted by glow) and it was positive. Now Glow has changed my estimated period dates and next months fertile window. My periods are  very regular, I'm confused as to why glow has changed the dates... And why I'm ovulating earlier than predicted.which is only a few days after my last period. Any help or insights would be great. Thanks ladies.