A little confused

<a href="https://play.google.com/store/apps/details?id=com.glow.android">GLOW app</a> is telling me my due date is April 14 and that I’m 4 weeks and a few days. NUTURE app is saying I’m due April 13 and 4 weeks and 1 day. Kaiser online is saying my due date is April 13 and I am 5 weeks.

My last period was July 7.