Hiv queries. And cause a false negative?

My 4th generation antigen and antibody test which was done 6years after possible exposure is non reactive. I have done it thrice and all are non reactive. I have no symptoms of Hiv. I have done HIV 1 RT PCR test and Hiv 2 RT pcr test. Both came undetected. But it was written in the report that the tests cannot detect viral load if it is below 100copies.my question is:- 1)Had I been infected by HIV 6years back can the viral load be less than 100 copies even after 6years when I am not on any medication? Or will my viral load level increase by significant amount? 2)I have done 4th generation CMIA antigen and antibody test after 6years.But while I did the 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 and cause a false negative?