thats a strange story,...why dont you go to a clinic and tell them to test you for every known std?,..or try another hospital..other than that you could buy some amino acid l-arginine and take 3000-5000mg of that and will show signs if you have herpes in a matter of days maybe even hours. youll get trembly and get a cold sore or rash/pimples/blisters with mild depression,fatigue and moodswings....(yeah! its a fun disease huh!)
only other thing that comes to mind is chancroid or secondary syphilis but if your ex tested positive for hsv2 it cant be either one.???
it may be that your viral load is so low and dormant that your immune system doesnt see a need to produce antibodies?,...you may need a very sensitive test like a pcr or something similar...