confused

Ok so I decided to go on the pill a few weeks ago. My doctor told me that when my period starts I should start taking it and carry on taking it until the packet runs out. I have one pill left for this month so I'm guessing that means I should start my period in a few days? But on <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> it says I'm not die on my period for another 16 days ( I started my last period over 3 weeks ago) I'm so confused. Please help