If you had muscle atrophy and it was due to ALS, you would have weakness. Furthermore, given that you have also had a clean EMG, then whatever problems you are currently having are not due to ALS. It's as simple as that. It appears as if you googled "muscle twitching" and got scared of it being a symptom of ALS. Muscle twitching in the absence of denervation (you don't have denervation because you had a clean EMG) means absolutely nothing.