Period is late

My period is late by 3 days and it’s usually right on time give or take like a day it’s never been 3 days late. I’ve been moody and so I took a digital test which told me I’m not pregnant, but something feels not like my normal self. I had an HSG test done in March would that have anything to do with my period? Or am I still just testing too early? I got sad when I saw the “not pregnant” but I know my period, it has never come this late in my adult life. I’m so tired of playing the waiting game my husband and I have been trying for a year and a half, and now my body is playing tricks.