Hello and welcome to e health forum.
One of the main problems in relying on HIV symtoms themselves is that they are notoriously vague and almost all the symptoms may in fact be symptoms of a different disease.
HIV DNA PCR test - has zero false negative rate, and hence if a test is done after 2 weeks of exposure and the test is negative, it is definitely confirmatory of a HIV negative status.
Since your test was done at 28 days, it is definite that you do not have HIV infection.