Ok, dear. Here are some facts for you.
1. Almost everyone has one limb that is a smaller size than another is.
2. Weakness ALWAYS precedes atrophy--major weakness.
3. ALS at your age is almost unheard of. Nearly 1 in a million odds if not more. There are about a dozen people with als worldwide that are under 20.
4. CLEAN EMG and CLEAN Neuro clinical exam means there are no upper motor neuron issues (reflexes, clonus, spasticity) and LMN signs are ALWAYS in an EMG.
Yes, sometimes they misread a dirty EMG--and tell people it's something different. But no, a clean EMG in your limbs means there are NO LMN signs anywhere.
Stress while in college is quite common. You're doing more walking now, I'm assuming, to get to classes? Carrying large bags of books?
As for the throat issues--it's entirely possible you have something called gastric reflux--which can be easily treated with OTC medications.
If food was staying in your throat for 2 hours--you'd be a medical first. If food is coming back UP--that can be a stomach problem.
I doubt you need to change your field of study--but you certainly need to work on the major anxiety--but if you aren't going to believe anyone here or doctors--there is little we can do for you.
i wish you peace.