Why are doctors so hesitant to diagnose lupus? I have several symptoms and positive sjogren's ss-a.

Prob u don't have it. Systemic lupus erythematosis is one of dozens of diseases grouped into the category of autoimmune connective tissue diseases. Many of these do not fit nicely into one, so that one can have a 'mixed' connective tissue disorder, or have an overlap of signs & sx. It may take years of following one of these unclear disorders to see a pattern. U probably have sjogren's disease, period. C rheumatologist.
Complicated. Such a complicated answer. Patients can have symptoms of lupus early on and then develop another type of autoimmune disease in the same family, or vice versa. Oftentimes in early disease the labs are difficult to interpret and can be misleading. It is also important to be rather judicious in diagnosing diseases like lupus for health insurance reasons, psychological stigma, etc.