Period 4 days late and negative pregnancy test

Maria

My period was due on 5/15. I took a pregnancy test on Tuesday morning which was a clear blue digital and it came back negative and then I took a clear blue rapid this morning which was negative. I have been having some nausea and feel like I’m urinating more. My period is never this late. It is usually right on time or maybe a day late. Any advice or has this happened to anyone? I have read that first response is better than clear blue but not sure how true this is