Pregnancy possibilities on your period!

Hey all! I recently got this app to try to figure out what the chances of getting pregnant are if you are having unprotected sex while on your period. If anyone has any insight into this, please feel free to share. I know that it's a possibility. I am just curious how high that possibility is. And if it matters if that period was Emergency Contraseptive induced. I'm going on day 9 of my period (pretty normal for me) and I had unprotected sex on day 7. Sooo, what are the odds? At this point I don't mind if I am pregnant or not. Any feedback would be great!