Negative pregnancy but still late…

So a week ago had a physical, usually get my period on the 1st or 3rd but I’m late. The test at the doctors office was negative. So was it too early to detect or could it be I’m late cause of stress. I have 3 kids already. I’ve been getting sick 2 weekends in a row on Saturday spent the whole day throwing up everything that I ate or drank. I been bruising easily too. Had horrible headaches and back pain off and on for a while now. I just don’t know if there’s a possibility I might be pregnant or just stressed.