Need help with operating this app

As easy as it might seem, this app confused me a bit. I just got pregnant, know my conception date, enter the first day of my last period and the duration of last cycle (although it asks me about the "duration of my last period" with 20-40day options). The result I get is the 5-week old baby, which is significantly wrong and quite certainly impossible. What am I doing wrong, and is there a way to synchronize or import my info from the Glow app which has all my period logs and durations?
Suggestions would be highly appreciated !
Thank you.