We do not see HIV passed through oral sex, with or without a condom. See our Know Your Chances – Oral Sex for risks associated with oral sex.
Regarding your testing, you’re correct that different HIV tests have different window periods. In order for your test results to be accurate you need to be past the window period for the test. The 3rd and 4th generation HIV tests would give you a final result after 3 months, but it would be unusual for the 4th generation test not to pick up HIV by 6 weeks.
You might be exposed to other sexually transmitted infections like Gonorrhea, Chlamydia, or Syphilis, from oral sex, though. It’s a good idea to get tested for these regularly if you’re sexually active. Using condoms for oral sex can protect you against many of these infections.
Also, it’s very common for people to experience stress and anxiety after having new sexual encounters. For more ideas about how to manage these feelings check out our Worry & Anxiety page.
Hope this helps. Please feel free to comment below or submit another question as needed.