11 days late and pregnancy test is negative

Hello, everyone! Has anyone here ever encountered a situation where their menstruation was delayed by 11 days, but the pregnancy test came back negative, only to later discover they were actually pregnant? My most recent menstrual period was on September 21, and I last had intercourse on September 26 (using the withdrawal method). Do you think there's a possibility that I might be pregnant now? Are there alternative tests besides the pregnancy test kit that can identify early pregnancy, or should I wait a few more days? Just a note, I haven't experienced any symptoms so far, except for increased bowel movements (no constipation)