Trust your 29 days Duo test, it is conclusive
The type of test you took is conclusive at 28 days and beyond so as Diver58 said, your 39 day test was conclusive so should be trusted.
Beyond that even, you never had a risk for HIV in the first place. Giving oral sex to someone is not a method in which people get HIV. Saliva has enzymes in it that breaks down the virus and air also inactivates it. The only risks for adults is unprotected, penetrating vaginal or anal intercourse or sharing of IV drug needles.
So, you have no worries about HIV from your exposure.
You did not have a risk, you did not need to test. It does not matter even if you had bad oral condition, saliva has proteins that inhibits the virus.