Birth control logging

J

I had the Nexplanon Birth Control Implant for 15 months and I didn't have my period during that time. Now that I have had it removed I'd like to start <a href="https://play.google.com/store/apps/details?id=com.glow.android">tracking ovulation</a>, but the app keeps sating my period is over a year late. How can I fix that?