With your low index value, you need a confirmatory test, absolutely. There is a good chance you don’t have HSV 2.
We don’t have data on transmission of HSV 2 in gay men, and especially if it is oral only.
I would say bottoming with no condom and no antiviral medicine is the highest risk. Add Valtrex and the risk is reduced by 48%, add condoms and the risk is reduced by 96%.
But before worrying about that, get a confirmatory test! Have your other IgG numbers been very different?