Fertile period and the pill

I'm on the pill but I want to know when my fertile period is so I can avoid that time for having ... But <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> doesn't tell me. I only got the app at the start of the month will <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> tell me or is it because I told <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> I'm on the pill ?????