I started spotting on August 1st 4 days before my period?

My last menstrual period was on July 5th lasted 7 days i had unprotected sex on July 17 .. i started spotting on August 1st 4 days before my period , the spotting lasted 2 days.. not sure if that’s implatantion bleeding? Or just a sign that I’ll be getting my period.. I’m a day late on my period. Took a pregnancy test today came back negative.. how many days should I wait to retake the test? Or am i not pregnant?

Age: 20
Female
Medications: None