Using OPK for the 1st time

Nicole
Hey Cysters,
My husband and I are just starting to TTC. I have my AF every month, though the cycle can vary from 26-42 days. I've been using the Clear Blue digital OPK since the 11th day of my cycle. I'm now on my 18th day (most fertile day according to Glow was on the 16th) and still haven't gotten that smiley face, saying that it's BD time. 😔 Though, we've been doing plenty of BD just to make sure. 😉
Anyone else in a similar situation? Is there anyway to tell if you're actually ovulating or not, besides blood tests and OPK's? My CM is definitely there and very plentiful, but the test just hasn't shown a positive for my fertility yet. 😕 Hoping this doesn't become a trend in the months/years to come!