I would say that at 3 months, the likelihood that you would serconvert if you were actually infected is at least 90%. It is correct that if you are HSV 1 positive, seroconversion might take a little longer. What is your HSV 1 status? Also, your risk of contracting HSV 2 at one encounter is really quite small. If I were in your situation, I would probably not test again, but if it would make you feel more secure, I would recommend that you do it at 4 months or 5 if you are HSV 1 positive.
Terri
Just to be safe i would take one more std test sense you are hsv 1 positive. It can take longer for antibiodies to build up in the system. Its also true your outbreaks will be less severe if you have hsv 1 as well. So you could mistake an outbreak for something else.