I can give you the window period for the 4th generation HIV test we use in BC Canada. The window period is the time between when a person comes in contact with HIV and when HIV will show up on a test.
We find that the 4th generation HIV test is 95% accurate by 6 weeks and would give you a final result by 3 months. Given that you had many tests all the way out to 19 weeks I would say that you do not have HIV and no further testing is required.
Please leave a comment to let us know if this answers your question or if you need more information.
For other readers, please feel free to leave a comment, or let us know if this was helpful.