Have you tried the carrot salad? (I know it's a meme but it's really powerful)
If not carrot salad, then white button mushrooms?
I had all your symptoms, I supplement T3/T4 now using Idealabs Tyromix. Plus, I do mushrooms daily since the carrot salad became too powerful (when I first started, it was just right).
This has radically reduced my symptoms.
In this, you haven't mentioned much about the food that you're eating which would also be helpful.
For example, you need a good source of B vitamins + other good stuff (liver) and other important vitamins and minerals (oysters). Do you have a clean source of milk and cheese and eggs?
Have you limited what you are eating to nutrient dense foods that I have listed above + some more?
Fiber and iodine won't help you. Thyroid will help but it will hurt more if you don't have your diet right.