Your test was 100% conclusive. No experts recommend testing after 6 months anymore. Three months post-PEP is fully sufficient to ensure that you do not have HIV. Whatever is causing your flu has nothing to do with HIV. People get flu all the time and do not have HIV.
Forget about HIV and move on - you do NOT have HIV.
1. Your risk was substantially low for PEP, an experienced HIV specialist wouldn't recommend you PEP for your risk.
2. You have tested at the correct time frame post PEP for a conclusive antibody test result. You have tested negative. You do not need any further testing.
3. Your undetected RNA PCR is a solid indicator that there was no viral genetic matter found in your body, RT RNA PCRs are hypersensitive tests, theoretically, they can start detecting 72 hours post infection.
4. I am confident that you have already read a lot online and the only reason you are coming here to describe your symptom is because you are most likely doubting delayed sero-conversion. Be assured that is not the case with you, unless you are on chemotherapy, had an organ transplant or a body part was amputated lately.
You are home safe. Please see your doctor for your ailments. You have nothing to worry about any more.