Positive culture .. negative blood tests results for herpes?

I recently got a blood test for herpes because back in mid february I got a swab done on a sore on my vagina ... I can count on my one hand how many guys I've had sex with all with a condom an none of them have herpes ... I've been in a relationship with the same man since 2008 he got tested an came back negative an I haven't been with anyone else I also had a bacterial an yeast infection. At the time of this swab .. I have had a lot of problems down there since I got pregnant wit my son .. now 14.5 weeks later ... my blood test came negative for genital herpes. So what do I believe?