Period late when normally always on time

[LisaDav]

Hi all,
My period is 3 days late, even though I'm regular like clock work. Ive taken a pregnancy test, and it's negative.
Any one know what might be causing this?
Tia - lisa x

Are you sure you're regular. I thought i was about 28 to 29 days until i tracked and looked through my app. My cycle varies from 26 to 32 which is normal for me. After 5m of 28 day cycles i got my period on day 31. Seems normal so far.

The heat sometimes does this to some people.