Slightly confused....

I'm officially a day late (based on 28 day cycle). I took a test, and it was negative.

The thing is, I haven't had a full cycle in YEARS. Last first date of menstruation was 9/13/19. I have no clue how long my cycles are. We are TTC so I'm just slightly confused as to why I would get a negative test even if I was "supposed" to start again today.

ETA: I had Mirena in for over 4.5 years. It was removed on 9/11/19; that is why I wasn't having actual cycles. My periods stop completely after about 6 months w/ Mirena.

Any tips? Advice?

What's your cycle length? At what point should I bring it up to my doctor? Should I retest? If so, when?

Thank you all for your help! And BabyDust to all!!!