I'm a 24 year old gay male from who was the receptive partner in an unprotected anal sex encounter with a gay male acquaintance around December 21st, 2007. He ejaculated in me. He and I actually volunteer for the same AIDS awareness organization. We have both been trained in STD/HIV prevention, but we obviously let one time slip. He works as a transporter at a local hospital, and he told me he was tested and HIV- as of two weeks prior to us hooking up. I was tested using the 30-min blood test on February 21st, 2008, allowing myself 8 weeks. The result was negative.
My question is this: In my research I have found that 2 months is, for all intents and purposes, sufficient time for the antibodies to appear. I am a bit of a hypochondriac, however, and I'd just like to know whether I should concern myself about waiting another 3 weeks before the 3 month mark. What is the likelihood that I would receive a positive result in another 3 weeks?