Welcome to HCM.
Your sexual encounter is a protected one. The chances of getting HIV
through unprotected oral sex
is negligible. So you need not worry much.
Anyhow, Antibody test done at 8 weeks is better to be repeated after another 4 weeks (12 weeks after the risky contact) to be more confident about that you are free from HIV. To avoid confusion get it done at a recognized medical laboratory.
Good luck to you.