Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Bulbar onset ALS occurs in 15-20% of ALS patients, most often occurs in older patients (around 70 years old) and is less common in patients in their 30s. Limb involvement occurs within 1-2 years in the majority. Symptoms of bulbar ALS include tongue weakness and fasciculations, inability to swallow saliva leading to excessive oral saliva with drooling and difficulty swallowing.
In general, if a patient is having weakness of the hand and foot, then an EMG would have picked up ALS even if the twitching is localized to the tongue. The diagnosis of ALS requires EMG abnormalities to be demonstrated in at least 2 areas of the central nervous system, and while in some cases jaw or tongue EMG is performed, this is not always necessary for a diagnosis to be made if abnormalities in the limbs or other muscle areas can be demonstrated.
Continued follow-up with your neurologist is recommended, and discussion of the above question and your other questions and concerns with him/her is important.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.