I would agree that your transmission risk is low, and I base that off of medical literature not just a guess. Here are two links that get to what your asking, which is essentially a numerical probability based on multiple factors (acts and treatment type) https://academic.oup.com/jid/article/198/8/1098/879583 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4006256/. I would encourage you to get tested if you are truly concerned.
Agree with cris. I would also add that herpes rarely goes from the genitals to the mouth. Oral hsv2 is rare, so if he has hsv2, it would mean that your chances are really low.
To clarify, there is no actual thing as "specifically anal herpes". Herpes infects nerve groups, and genital herpes infects the sacral ganglia, meaning that it affects the entire genital area. Outbreaks will often appear in the area that you are infected in, so if he was infected anally, he might be getting outbreaks there, but he is also infected in the rest of his genital area.
And he is on Valtrex, which reduces his shedding.
But still, I agree, that your risk is very low. I wouldn't worry at all.