Welcome to the forum. But apparently you missed the opening statement at the top of the forum, which is limited to STD questions other than those related to HIV/AIDS. Accordingly, my reply is brief and there won't be an opportunity for follow-up discussion.
I agree the choice to have commercial sex in South Africa wasn't smart, but you were sufficiently wise to use a condom. In any case, test results always outweigh exposure history in judging whether or not someone was infected, and your negative test at 8 weeks is definitive: you were not infected. The test detects any HIV infection anywhere in the world.
Because many experts continue to recommend a 3 month test for definitive results (even though it really isn't necessary with standard tests in routine use), you might want to have another test at that time. But in the meantime you can be 100% certain you were not infected.
Regards-- HHH, MD