As I said saliva test for Iodine is a bad test. If your not doing a 24 hour loading test then that also isnt accurate.
chronic fatigue has a lot to do with adrenals and many other things whats the rest of your supplement plan look like? I doubt anyone is only deficient in iodine.
Paint a circle about half dollar size on inner arm and see how long it takes to fade. The faster it fades the more deficient you are. If its still there 12 hours later or so then your likely sufficient.
And yes, all the nutritional cofactors can have a big impact on your bodies ability to make use of Iodine and have a dramatic effect on your fatigue.