I'm super confused. I should be 21 dpo today, but I just got another BFN and no AF. How is that even possible?

I also O'ed super late this cycle, so my last period actually ended on Jan. 3. I suppose I could have miscalculated my O date, but I had a peak reading on the clearblue ovulation monitor, which corresponded to temps and CF indicating ovulation. So I'm pretty sure I got the ovulation date right, but then how could I be 21dpo with no period and BFNs?

I just weaned in January, so it makes sense for my cycles to be messed up, but I didn't think the luteal phase was supposed to be this erratic.

Not sure what I'm asking. Just wanted to see if anyone has ideas of what might be going on.