Hello. Welcome to hcm
As you have already been tested for common STD's,there is no use of repeat testing unless you are so concerned but there is a special entity in HIV
called window period. Where all the parameters will be normal and test negative. Here,there wont be any fever
too but once the patient crosses window period,that the symptoms start and tests will be negative.
I advice you to undergo a repeat test at 12 weeks is enough for HIV to rule it out and if you are so concerned,you can undergo other tests for STD's too. Dont start any antibiotics as they might give false negatives again till you get the tests. There wont be any special use if you test it at 6 weeks.
Also,get counseling sessions about dangers of sexual contact with a unverified partner.
All the best