Irregular AF & TTC

So I went off the Nuva Ring in July 2017. My first five cycles after I went off BC were all 28 days long, then my sixth cycle was 39 days long, & the seventh was 28 days long. Now here I am on cycle day 30 & I tested today & got a BFN. It’s so annoying because I don’t know if I’m actually out because I have no idea how long my cycles are supposed to be! Glow is estimating that I’ll start AF tomorrow. How do you girls with irregular AFs determine when AF is late & when to test?! This is driving me bonkers lol