Kelp and other seaweeds, living things from the ocean. Very difficult to get enough iodine without supplementation, when our health can benefit from 50-100 mg, and possibly more. Sounds like you've been colder and colder these last few years. It probably will be difficult to get your health back, but not impossible. Well worth the struggle. You will need to heal both your thyroid and your adrenals, at the minimum. Besides beginning a nutritional program using Iodine and its support nutrients, with good food and good oils, salt, and water, you may need to consider temporarily using thyroid glandulars to allow your body to take in nutrition more easily. To understand the scope of what you're facing, consider viewing this excellent, friendly lecture/slide show by Dr. David Brownstein, one of our Iodine Docs. The link is to Part 2, but by replacing the "2" with either "3" or "4" you can also view Parts 3 & 4. Also, to understand hypothyroidism from a patient's point of view, visit Stop the Thyroid Madness.
Agree with GodAintDoneWithMeYet. Some are lucky regarding their thyroids. But iodine deficiency can show up in other ways. You've gotten your wakeup call now. Be thankful. Years down the pike, when your friends have prostate cancer, breast cancer, even thyroid cancer, you will seem "lucky" to them.