Hiv testing authentication. Test?

My last possible exposure was 6years back. I have no symptoms of Hiv. But after 6years I have done 4th generation CMIA antigen and antibody test which is non reactive. I have done it thrice and thrice they are non reactive. I have done HIV 1 RT PCR test which came undetected. I have done HIV 2 RT PCR test which also came undetected. But it was written in the report that if the viral load is below 100 units then it cannot detect it. The questions are:- 1)Had i been infected 6years back and as i am not on any ARTs, can my viral load be below 100 even after 6years?or had i been infected it would have been more than 100 to be able to be detected? 2)While i did the antigen and antibody test i was using corticosteroid nasal spray to treat allergic rhinitis for a continuous period of 5months. Can this corticosteroid nasal spray to treat allergic rhinitis for a continuous period of 5months cause immunosuppression and reduce the HIV antibodies so that it cannot be detected by HIV antibody test?