at 2- 3 weeks from exposure, about 50%will have developed antibodies. at 12 - 16 weeks, it's about 80%. at 6 months, it's about 99.9%. a small % will never develop antibodies.
asha recommends testing at 12 - 16 weeks, so the person will get a fairly reliable result.
Sorry to hear this... this was how I got mine... his blister had healed up 2 weeks prior to me recieving oral sex and I got Genital HSV1 from him.
I would recommend going to the doctor and getting tested for piece of mind.