I noticed you said KI, not SSKI . Do you have a breakdown of how much Iodide per gram is in the KI you are taking? For instance, Trapper's SSKI contains 764 mg Iodide per gram of SSKI .
It just made me wonder whether your KI is weaker, and you may not be getting as much Iodide as we think. My understanding is that 4 grams of SSKI would pack quite a wallop and might be difficult to sustain for very long.