Period 3 Days Early

Wondering what it means if my period came 3 days & was only 3 days long, much lighter then usual? My period is usually around 5 days & is never early. I’m two months TTC. Took my pregnancy test the 3 day of period because I thought something was off, but it turned out negative. I’m assuming it was just an odd/off period. Just wondering what everyone thoughts are??