Glow app

I'm confused. It might be an easy answer but I had to ask...
My <a href="https://play.google.com/store/apps/details?id=com.glow.android">Glow app</a> changes on me. Idk if that's what it supposed to do. I really just want to know when my fertile days were. My last period was on September 18th. According to my app, I ovulated around the 29th. I haven't gotten my period this month so I tracked it on Glow & now it's stating that I ovulated on/and around October 11th. Is that accurate?