Welcome to the forum.
Your question is one that allows an accurate reply based only on the title you chose, "HIV test after 8 weeks". Assuming that test was negative, you can be 100% certain you did not catch HIV. It doesn't matter what sort of exposure you had or any symptoms you may have experienced. Test results beyond 6-8 weeks always overrule all other considerations. For more detail on this, see this thread:
http://www.medhelp.org/posts/show/1704700.
Now I have read the rest of your question, and also see you asked the same one on the HIV international forum. As implied by the above comments, I agree with the advice you had there from Dr. Cummings.
As for "the one thing that keeps me worried is that since the 5th week I have been with a sore throat...", see my comment above about symptoms and test results. Your tests prove that HIV is not the cause of your sore throat. And anyway, sore throat by itself is never a symptom of a new HIV infection.
"should I get another test?" No. All is well; no further testing is needed.
Best wishes-- HHH, MD