Period 4 days late on Paragard IUD???

I always have very regular periods, in fact I went back to check and they have ALWAYS been right on the money coming on the day the app says it will never early or late for the last 8 months since I got my period back after having my youngest. I took a pregnancy test the last 2 days both negative but I’m wondering is it possible that I could have ovulated extremely late so I’m not getting a positive yet? Because with my both my kids I got a positive only 8 days after ovulation. I’m not testing again until Friday morning but this is so weird for me because they’re never irregular. Also I’d like to add that there is nothing different that would cause this, I’m not stressed, or taking any new medications, no lack of sleep, also I don’t have PCOS