Crazy

Jessica
Ok so my period was to start on the 1st of the month. I have never been late. I took a digital test Sunday morning and just now both said not pregnant. What's going on. Been sick the last two nights within 10 mins after eating but not a whole lot. I am always on the 28th day cycles but never one day late. Should I try the first response test that isn't digital or am i just too early to tell?!