Sorry to hear. Some people have no hair shedding problems on keto, but many do. This is most likely due to not getting sufficient sugar in your diet, which is essential for thyroid health. Personally, I struggled with this same problem for a long time and even now over a year later my hair has not yet recovered 100%.
I would suggest eating more fruit for starters.
Also, my thyroid tests also came back "normal", whatever that is supposed to mean. My understanding is that doctors do not test the thyroid in enough detail and misdiagnosing or under-diagnosing is a very common occurrence.