They say the average person produces detectable antibodies 2-4 weeks after a possible exposure (i think). So if you test 6 months after a possible exposure (like i did), you should definitely have enough antibodies, but what makes a person take longer than 6 months to produce detectable antibodies???

An underlying health condition such as Hepatitus C, Cancer, or some other underlying illness will cause some people to test negative past 6 months. If you have one of those problems, then you have a lot more to worry about than just HIV. I am sure you would probably know it if you had one of the other conditions.