I tested HIV negative after 21 weeks of unprotected sex. Were those results conclusive?
Thank you for your inquiry. From what we gather from the question, you were asking about the conclusiveness of HIV test results 21 weeks after possible exposure. Depending on the type of HIV test, the window period can range from 3 weeks to 12 weeks. At 21 weeks, the test results can be considered conclusive. HIV testing guidelines for British Columbia state "Most patients can be tested at 4 weeks following exposure (>95% of infected individuals will have detectable antibodies at this time). If negative, repeat testing at 3 months is recommended (>99% of infected individuals will have a positive EIA at this time)." 
Recommendation: Refer to a physician for other health-related questions.
Regards, AIDS Vancouver Helpline/Online, Ashley
- HIV Testing Guidelines for the Province of British Columbia [Internet]. Www2.gov.bc.ca. [cited 10 September 2018]. Available from: https://www2.gov.bc.ca/assets/gov/health/about-bc-s-health-care-system/office-of-the-provincial-health-officer/hiv-testing-guidelines-bc.pdf