I use 500mg valacyclovir irregularly (i.e. not on a daily basis but maybe 2-3 times a week). i'm getting frequent hsv2 outbreaks. could irregular use lead to frequent outbreaks?

Maybe not herpes: What does "frequent" mean? Genital herpes due to HSV2 doesn't recur more often than once a month, and even that is unusual; every 6-12 weeks is most common. Symptoms more frequently than that is caused by something else, regardless of how often you take valacyclovir. Stop VCV for a while, then see your doctor for evaluation and probable HSV test while you're having these same symptoms. Good luck.