Hi Grammie:
Unforetunately with most immune disorders a lot of the symptoms are the same, fatigue, depression etc but then there are usually other symptoms that convince doctors what sort of immune disorder you possibly have if any.
If you have read my sticky you will know I have Scleroderma this is linked to Lupus. It took about 2 years to get a diagnosis & I actually have the antobody present in my blood (not all do) I dread to think how long it would take to get a diagnosis without the antibody showing???
Hypothyroidism can be an immune disorder so that on it's own can cause the fatigue you are suffering & the depression & quite often someone with an immune disorder may possibly have other immune disorders.
It may well be that your hypothyroidism has worsened, has this been checked recently or maybe that it is getting the better of you.
All I can suggest is carry on with the tests to see what shows, if nothing ask the doctor if the hypothyroidism is to blame.
Let me know how you go on.