To answer your question about what atrophy is, I had to have the Doc point it out to me. Actually every neuro I saw noticed my right (dominant) hand. Once they showed me what to look for, I saw it on my left as well but didn't say anything, wanting to see if they noticed. The ALS clinic's report says "muscle wasting" below both wrists.
Another hint: I noticed they measured my calves and so I do as well, every 6 months or so. Those muscles have stayed the same (thank goodness) but there is a noticible, and measurable difference in my thigh. The right one has lost an inch. Probably explains why it is so hard to climb stairs most days.
No DX yet and depending upon my mood, sometimes I believe I will stay the same for years to come. I have amended my lifestyle and given up some things but I no longer grieve the strength I used to have. Most days I am perfectly happy just the way I am, because at this stage no DX is a good thing, at least for me.