I second the vote for Daniel Wallace's book. I read through it cover to cover when I was going through the diagnosis process, and still refer to it - often.
I had an elevated ANA years ago - and my primary care doc warned me that I might be facing something autoimmune-related down the road. Sure enough! When I got really sick, my ANA was through the roof. But, until recently that's the only blood test that indicated lupus as a possibility.
You'll read in the book about the criteria they use to diagnose lupus. My rheumatologist was clear with me, though. She said that criteria is really only important for research standards. She treats many people for lupus who never fulfill the official diagnosis criteria. By ruling out other causes, a good doctor will still be able to make a diagnosis and get you started on treatment that should help.
"If you trust Google more than you trust your doctor than maybe it's time to switch doctors."