1) Is it possible/ likely that I could have HSV 2 and not pass it on to my husband after at least 4 years of frequent unprotected sex with him?
It is possible, yes. If this is indeed the case, it suggest that you aren’t shedding virus very often. You could obtain the western blot as confirmation of this result though it is pretty high. I have seen false positives as high as 17 and several at 12