I had negative combo hiv test at 6 months after sex. dr told me i need to test every 3 months but that was the only exposure i had. and ive had multiple rapid tests negative and finally combo lab test at 6 months? is there a need to test more?

You may have misunderstood your doctor, or s/he may believe you remain at risk, i.e. likely to have other high risk exposures. (Or s/he misunderstands HIV risk and testing, but that seems unlikely.) If indeed you have had only a single potentially risky exposure, your negative AgAb (4th generation, "combo") test at 6 months is 100% conclusive and no more testing is needed.

A negative 4th gen combo test at 6 months after exposure rules out HIV from that exposure. If you have not had any exposure since then, you do not need to test any more. For info: HIV test window periods https://www.cdc.gov/hiv/basics/hiv-testing/test-types.html Wish you good health!