It’s not possible for someone to say that someone has HIV because of a low percentage of lymphocytes and the symptoms you described, as this can be caused by other medical conditions and is not specific to just HIV. But I could see why someone would be concerned especially after a sexual risk that could have passed HIV.
A HIV test is really specific for HIV and since you did the test at 3 months it would be very accurate. Given this I would say that it is not HIV that is causing this problem for you and a HIV PCR test would not be helpful.
I would talk with the health professional who ordered the test for you. It would be good for you to have a conversation with them about your blood test results and the symptoms you are having. Hopefully they would be able to give you some idea of what could be causing the problem or do further investigations to see what could be going on.