If you have "terrible atrophy", what is it that you cannot do? Atrophy comes after a muscle becomes useless and, in the case of leg onset ALS, one cannot go up on their toes or back on their heels. They don't get tired from doing that, nor is it difficult, they simply cannot do it. Not even a little bit. As a result, the lower leg then starts to atrophy.
So, again, which muscle function has died that has caused this "terrible atrophy"? What can you no longer do that you once could? You have no signs or symptoms of ALS, and nobody but you thinks you do, so I'm wondering how you came to the conclusion you have atrophy and a leg that "looks like bone".
I apologise for sounding harsh, but I want you to look objectively at what makes you think about having this disease over a four and a half year period. Whether you have consistently or intermittently, the fact that you don't have this disease yet won't stop thinking this, should give you a pause for concern.