Welcome to the forum. Thanks for your question.
The HIV ELISA tests are among the most accurate diagnostic tests that exist, for any medical conditions; and they are 100% reliable 3 months after the last possible exposure. (Even 6 weeks usually is sufficient; see the thread linked below for more information.)
Therefore, negative HIV test results results always overrule exposure history or symptoms. There is no such thing as delayed positive test results because of immune compromise. The only possible exception is profound immune compromise of the sort associated with terminal cancer and other immediately life threatening conditions, or treatment with potent chemotherapy or high doses of other powerful immune suppressing drugs. Even these conditions are mostly theoretical, with few if any actual cases in which there was real interference with HIV testing.
That other thread is at http://www.medhelp.org/posts/show/1704700
So no worries -- you can be 100% certain you didn't catch HIV. There is no need for additional testing at 6 months or any other time. If you have a regular partner, you can safely continue unprotected sex without worry. But next time you have a commercial or otherwise non-monogamous sexual encounter, please use a condom!
Regards-- HHH, MD