I took hiv rapid 3rd generation after 4months possible exposure, result is negative, but i afraid that i have weak immune system that might affect the result, some doctor here said wait 6 months, should i get tested again ? im very very scared. help?

Get a 4th gen Combo test at 6 months and if that is negative, it will rule out HIV, you immune system status notwithstanding. For info: HIV test window periods https://www.cdc.gov/hiv/basics/hiv-testing/test-types.html

Ninety-seven percent of persons will develop antibodies in the first 3 months following the time of their infection. In very rare cases, it can take up to 6 months to develop antibodies to HIV.