Bit paranoid about poss. exp. to hiv. 4th gen and rapid (2-4 wk test) came back neg. twice at 2 weeks, & neg. twice at 1 month. did a 5 month 21 days test and came back neg. do i still need a "6 month" test? or can i definitively say i'm negative?

Negative: The 4th generation HIV tests are the most sensitive tests modern medicine has to offer for any disease. False negative rates are essentially 0 and re-testing repeatedly is not helpful unless you've had repeated risky contacts. The test combines HIV RNA (virus itself) detection with antibody detection, so a waiting period is not necessary after exposure as was the case with older tests.