3 days delayed

So my period seems to be 3 days late according to this app my last period was on April 20th to the 23rd they are in regular I had sex on May 10th Mother’s Day but with a condom said it didn’t break I took a pregnancy test the day after Memorial Day using first morning urine and the test came back to be negative I know it’s 3 days left in this month I have seen dry white discharge in my underwear