Average cycle length

Amanda • Married 6 yrs. Have 1 son. 1 daughter in heaven... She passed from SIDS 5/21/13-6/9/13. Now TTC #3 (our rainbow baby)
We've been TTC for 5 months now. My cycles are 35 days apart. I've had a hard time determining when I'm ovulating. I've been using the Glow calender, and not sure how accurate it is. Anyone due for AF on or around the 21st?