Late period but negative test

Rikki-le
My last period was april 20th-23rd. Ovulation was may first. I had sex April 30th...The first...Second ..and third. Of may.. . Next period was scheduled for May 17th it's the 19th and haven't started. And normally it's on time. I took a test today , the 13th and the 10th of may and All the tests are negative. I am stressing. Has this happened to anyone? ?