Hi. I'm sorry you're frustrated, I know what that feels like. Here are a few thoughts & I hope others add more.
Have you seen a gastro & had a colonoscopy, to rule GI AI's (like ulcerative colitis, Crohn's, Celiac) in or out?
How about thyroid function tests? I was surprised to learn that skin problems are seen in more AI's than I ever realized. I knew about skin & lupus, that one was obvious---but not that skin problems (incl. hives) are possible in Hashimoto's thyroidism and in some of the GI AI's, etc.
Re: edema in legs, was urinalysis run?
I was dx'ed with lupus but did not test positive for anti-ds-DNA or anti-Sm, two autoantibodies that are in the lupus diagnostic criteria; instead mine was anti-Ro, which is seen in both Sjogren's and lupus. The moral of this is that many antibody tests need to be run, not just the several that are formal criteria. Did you see a whole slew on your labs? BTW, you could read those diagnostic criteria on the lupus board in the "sticky post" (permanent info post) section, which you'll see directly above the user threads.
I think long-standing infection, either bacterial or viral, can also deplete WBC's.
Hope others add more ideas &/or expand on these. It's frustrating, but I think you're seeing various specialists is definitely the right move. (I'm in that mode myself & can't even guess which specialist will hit the jackpot, urologist, gastroenterologist, or GYN.) Hang in there & let us know what happens next, OK? Best wishes, Vee