I knew how many weeks along without a doubt my last pregnancy since I had clockwork 28 day cycles. Since stopping birth control and starting trying to conceive baby 2, my cycles changed to 28-35 days. This cycle I ovulated on cycle day 19/20 and was supposed to start my cycle on Sept 20 (predicting a 32 day cycle from my ovulation date). I used ovulation kits.

Glow <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">Nurture</a> is tracking me at 4w3d but Glow is tracking me at 5w0d based on LMP. Which one is right and how do I calculate weeks along when the cycle is longer?