Hi. I'm sorry you're struggling. ANA is a very "general" test, unfortunately; so in & of itself, it can't diagnose anything. That said, do you know how high your ANA results have been? (The higher ANA is, the more likely a true AI condition. But *lower* positives are possible due to a passing viral or bacterial infection, due to a family tendency, etc.)
Also, I'd want to know exactly which *more specific* tests the rheum has run. Those would give strong hints as to which conditions he's considered. You could get copies, then post all test names, adding the actual values & reference ranges for any that have been abnormal.
Some AI's can take awhile to build, so it can awhile for labs to catch up with symptoms, even when the "right" labs are being diligently run. And in some AI's, like RA for one, many people may not "present" with positive labs; and even worse, some people with RA NEVER turn seropositive for certain key tests. And these are only several examples of why the AI's can be extremely challenging.
Re your low-ish
iron, I think many women can have low iron simply due to heavy or prolonged periods. And do you have any GI issues? (GI conditions like Celiac can deplete iron, I think.)
Re hand pain, is in both hands or just one?
Re B12, I don't know in what conditions it typically depresses (sorry), so I hope others weigh in.
Were your thyroid values checked?
Sorry the above is sort of rambling. (I actually started with some relatively clear thoughts.

) Looking forward to hearing more & sending warm wishes. Bye for now.