Hello Dawn and welcome to NT!
I'm sorry that you're having neurological problems after having had to fight cancer.
Beyond knowing that the deterioration on your MRI is probably in the normal range for your age and probably not responsible for such severe symptoms, I'm afraid that I lack the expertise to speculate.
I do, however, recognize many of your symptoms. I damaged my spine in a car accident. Like you I have decreased strength in my arms and legs. My grip strength is fourteen (I was a super jock chick before) and I can't hold my arms out long enough to put bulbs on the Christmas tree.
I can't remember, did you mention tingles and spasms? Are they trying to dampen your symptoms with meds like Lyrica? (Probably not Lyrics since you said you weigh 105 not 205
My injury occured high up on my neck, so the neurological damaged is pretty much everywhere. It might be a good ides to find a clinician willing to map your nervous function to determine where the problem originates. If there is pressure on your nerves that can be relieved or if they've merely been bruised, nerves can regrow. At about 1mm a day, it's a very slow process. If nerves were cut during your surgery, your impairments could be permanent.
Nerve damage during surgery is not uncommon. Please make sure that the neurologist treating you has no connection to your surgeon. It's nearly impossible to get one doctor to rat out another. In fact, considering the impact this must be having on your career, finances, family life, etc..., you might want to consider consulting a reputable personal injury lawyer. Sadly, sometimes it's the only way to get to the truth of what has really happened to you.