The exposure that you described was close to no risk. If your partner was infected with HIV, your risk of acquiring HIV from performing oral sex on him it’s less than one infection in 10,000 exposures (I.e. That would be one infection acquired if you performed oral sex Ion an untreated, HIV infected person every day for more than 27 years). Further, fourth generation HIV tests provide conclusive results at 42 days following exposure. Your test at 40 days is virtually conclusive and the chance the infection would’ve been messed is negligible.  

Taking Val tracks has no affect on the accuracy of current fourth generation HIV test.

I urge you not to worry further about the exposure that is making you anxious. Your risk was negligible before you tested and your 40 day test results effectively prove that you were not infected. Personally, I see no reason for further testing. If you need to reassure yourself, test at 42 days. I am confident that that test  will be also negative. EWH