What is thisssss

So my period is like clock work.

This time is is 3 days (verging on a fourth) late... odd.

I’ve taken 2 tests that were both negative! 1 evening of missed period and day 2 of missing period.

I’ve not felt sick at all, or pregnant. (I have 2 children so know what pregnancy feels like)

I have recently started hanging out with a really close gal pal who also had a late period this month. Do you think it’s our cycles trying to sync up? Helpppp.