Clear blue fertility monitor - long cycle

I just got off bc in November. Since then I have had two 43 day cycles. I am currently on day 54 of this cycle. Not sure if I skipped my period or I'm still waiting. I know ovulated a month ago (I used opks). I'm assuming I'm not pregnant bc I've gotten a handful of BFNs. I just got my CBFM. Should I wait to use it until I see AF? Is it possible to skip AF? Not sure what's going on. I do track my cm so I thought about waiting to use my monitor until I see some change in that (right now cm is just dry...)