Help ... Question TMI !! Below

So my last period was Feb 28 . my period didn't come for March at all. Could it be because of the short month we had in Feb?? My nipples are so sore. And I have some cramps this morning but my nipples have been sore for 3 days now. I have two kids . 2 and 4. Never had any symptoms when I was pregnant except nausea. I'm thinking that the short month messed me up but not sure seeing how it's April now I took a test 2 days ago. Negative as of now.