Anyone else have this?

I had unprotected sex aug 13 with husband used withdrawal method, pretty sure I was ovulating at the time. That night I had very very faint spotting. The next morning faint spotting too (like one spot). So my period was due August 25 (normally always on time). 5 days late so far and no period yet. But I took a test every morning the past three days and all were negative.. what’s going on.