Here is what I have personally found to be true:
Hypothyroidism causes low stomach acid. (So do certain medications.)
Low stomach acid causes mal-absorption of nutrients.
Low nutrient levels of specific minerals can cause hair loss because the lack of specific nutrients exacerbates thyroid dysfunction. (Especially true for ferritin (iron storage) levels).
Nutrient reference ranges are used improperly. Being merely being "within range" (anywhere between 12 and 150 ng/ml) is a dangerous game to play when the optimal range for adequate overall body functioning and good thyroid function has been proven to require ferritin levels between 90-110 ng/ml).
"Normal ferritin levels for women are between 12 and 150 ng/mL. According to some experts, Ferritin levels of at least 40 ng/ml are required to stop hair loss, while levels of at least 70 ng/ml are needed for hair regrowth. The optimal ferritin level for thyroid function is between 90-110 ng/ml." (Source: thyroidpharmacist.com/artic...
Through my personal experience, doctors of conventional medicine mostly have no clue, as the "within reference range" mentality taught to them in medical school is used without question -- even as illogical as it is to the average layman. The body has optimal levels that need to be maintained for health. That has been established, yet ignored for profit.
Big Pharma continues to profit at a mind-boggling rate by making medications for "disorders" and "syndromes" they drum up and then entice doctors to prescribe for those reasons. The bottom line is that most often it is simple nutrient replacement that is needed to cure symptoms caused by a malnourished (and thus anti-thyroid) body. If the thyroid is not happy... your body will eventually be wholly sad.
I would highly suggest you have your ferritin levels checked and compared with the optimal range of between 90-110 ng/ml. Also check Vitamin D and some others and make note of optimal levels as recommended by functional medicine (its purpose is to restore health, not just quell symptoms). The article below will be of help to you in that regard in gaining an understanding of what is happening in your body that leads to so many symptoms -- including hair loss:
Healing Hugs to you!