Generally, the clinical examination and a careful history will enable the physician to make a diagnosis of Herpes. HSV-1 is most often on the lips and HSV-2 is the genital variety. These two are very similar and related viruses. The oral variety is usually spread by mouth-to-mouth contact and can occur from childhood onwards (social kisses). Genital herpes is similarly from genital contact and most often occurs when the person has become sexually active.
There is no cure for either variety. Antiviral drugs taken during the active phase of the disease can cut down the duration but cannot eradicate the disease. During the dormant period there is no discomfort and normally at no time is the infection life threatening or serious though in some very rare cases there can be a serious eye or even brain problem. The type that reoccurs on the lip is mostly a nuisance and embarrassment. Reoccurrence occurs more frequently at first but then becomes less frequent and generally may become completely dormant. Lab tests are difficult and I would tend to believe the opinion of your doctor. It is infected when the disease is active and you should avoid kissing and oral sex during such times. Research is going on but there is no breakthrough regarding cure at this time.