So my husband and I have been TTC for about 2 months now. My cycle average is 37 days, was on birth control for 10 years but have been off any birth control for almost a year. I've been using period tracking apps to track ovulation with no success on getting pregnant so I decided to do some OPK. Is any sign of lines like day 15 a LH surge or just when it's as dark as the control line?  It's kind of funny because my period tracking calendar shows next week as my fertile and ovulating days. So I've been a week off!