Getting social security disability benefits is not necessarily the difficult nightmare some will lead you to believe. If done properly, it can be achieved in a reasonable amount of time. I think it took me about two months, give or take a week or so.
I had the aid of a law firm that specializes in disability, which I am sure helped considerably. But the key to it all is the merit of your case: in short, do you deserve to be on disability?
I can't speak to your case, but if your lupus greatly impacts your ability to perform your job you should be and will be considered strongly. The key is to make a strong case in your testimony to the disability people. Make them aware of every illness you suffer from, and make sure they know of all the symptoms that cripple you and how often, etc.
To give you an example of who might get accepted, I suffer from lupus, interstitial lung disease (which has stolen 70 percent of my lung capacity), bipolar disorder and various vertebrae fractures as a result of high volumes of prednisone consumed over the last four years. I also battled lung cancer earlier, but overcame it with six months of chemo.
Your doctors' testimony obviously is crucial. They should support your claim if you are truly a candidate for disability. Above all, don't fret the time it takes to get this done. Just let the process take its course and you should be OK.