I had a high risk exposure during the last three months and I tested negative at the 6, 8 and 10th week using insti finger prick tests and most recently tested at the 12 weeks using insti HIV 1/2 rapid finger prick and the control dot appeared but looked faint and no other dot was there... How can I rule my test results owing to the fact that the control dot was visible but light in color
That faint line has no significance because it's an error, the test was administered incorrectly and it provided you with an indeterminate reading that has no conclusion. Since you used home testing kits, you would need to repeat the 12 week's test for a conclusive result. Although your 10 weeks negative changing ahead is improbable. You can walk in to a testing center or diagnostic laboratory for a standard test to stay away from hassles of above nature.
Just so you know, unprotected vaginal sex is classified as a low risk exposure for a male partner, most males don't contract this virus from just one episode of unprotected vaginal intercourse with an infected female partner. Also, testing such incessantly reflects anxiety, if you are still anxious after your 12 week's and contemplate various other may/might scenarios, you would have to see a therapist to seek help for this behaviour.