Iodine supplimentation

I received a big surprise today and it doesn't make sense to me.
I've been taking 10 drops of Lugol's Iodine in water plus raw apple cider vinegar for over 3 months, thinking that it would eventually replace my need for Armour Thyroid medicine. I had my blood tested yesterday to renew my perscription and the doctor called me today and says that she has to increase the dosage I take. Any theories as to why the opposite happened of my intention.