The risk is theoretical only. The odds are astronomically low, and you might just as well be worried about being trampled by elephants while you're collecting your lottery winnings. Put this incident behind you and move on.
Oral sex is not a risk for HIV.
Risks are:
1) having unprotected, penetrative vaginal or anal sex, or
2) sharing IV drug needles with other IV drug users.
Avoid both of those activities and you will never have to worry about HIV.