I have an unprotected anal sex with a unknown status male, I was in the incentive position, but I don't ejaculating inside. I tested hiv after 2 months, again 90 days again 8 months, again tested 17 months after the exposure, all results came negative. But still I am worrying, it was my first and last experience. Is there any chance of 17 months negative become positive later?. Really I am worrying, kindly give me a answer. Do I need to test again?