Oral sex isn't a risk for HIV. Air and saliva inactivate the virus so you never had a risk in the first place and never needed to test. The only ways adults get HIV is from unprotected vaginal or anal intercourse or sharing IV drug needles. If you don't do those things, you don't need to worry about HIV.
For future reference, the 4th generation Duo or Combo test is conclusive at 28 days and beyond and all others at 3 months.
But no risk from this activity is the main thing to focus on.