Hi and Welcome
I am sorry you are having such a difficult time right now. Lupus is very difficult to diagnose because it seems that no two people with lupus are affect in the same way.
There is no single blood test for diagnosing lupus. Systemic Lupus Erythematosis (SLE) is diagnosed using 11 criteria. If you have 4 out of 11 it is likely you have lupus.
Face rash, which doctors call a malar rash, that is butterfly shaped and covers the bridge of the nose and spreads across the cheeks Scaly rash, called a discoid rash, which appears as raised, scaly patches Sun-related rash, which appears after exposure to sunlight Mouth sores, which are usually painless Joint pain and swelling that occurs in two or more joints Swelling of the linings around the lungs or the heart Kidney disease A neurological disorder, such as seizures or psychosis Low blood counts, such as low red blood count, low platelet count (thrombocytopenia), or a low white cell count (leukopenia) Positive antinuclear antibody tests, which indicate that you may have an autoimmune disease Other positive blood tests that may indicate an autoimmune disease, such as a positive double-stranded anti-DNA test, positive anti-Sm test, positive anti-phospholipid antibody test or false-positive syphilis test
There is a bunch of great information in the Tips and Resources sections of this board (on the right hand side) I suggest you check it out.
Educating yourself is one of the most important things you can do for yourself. The Lupus Book by Daniel Wallace is considered by many to be the best and most comprehensive book about lupus. That would be a good starting point. another book I really like is called Lupus Q&A Everything you need to know by Robert Lahita and Robert Phillips. I like it because it is very easy to understand.
Good luck at your appointment! Please let us know how it goes
Lupylisa
With love, with patience and with faith, we'll make our way.