I got on the scale today and found I had gained 2 pounds. That's on top of gaining a pound yesterday. Why?
This is a mystery we all face from time to time. It can't be answered in a generic way, by NANY or anyone here. The tired old cliche YMMV (your mileage may vary) definitely applies.
As for those daily fluctuations? Water weight comes and goes with amazing shifts from day to day. Be sure you are eating enough salt and drinking enough liquid daily.
I doubt that there is much reliable research on weight management for people with disabilities that limit mobility. The pool of subjects is significant, but probably too small to interest most researchers. Also, like you, I'm in the post-menopausal category, where the "average" advice breaks down.
So, you are out of the "mainstream" in two categories. The only good answer is what works for you? That takes experimentation and commitment over time--which you seem to be pursuing to the best of your ability.
For the past five years or so, as I jumped into my 7th decade, I've found actual weight loss nearly impossible. I console myself with the fact that I'm not gaining at the rate I used to when I was not adhering (mostly) to LC eating. Also, research suggests that a little extra fat is a feature of longevity.
Don't drive yourself crazy trying to figure out the percentages, the calories, the quantities based on some online chart. Clearly these do not represent YOU. Besides, our bodies are just not that specific. Here's my suggestion (sorry if I'm repeating the basics you already know well):
--Adhere to a very low-carbohydrate menu. You know what foods to avoid: starches, sugar, fruit, most dairy. Use butter, mayonnaise, and fatty meats as much as you like. Think bacon, tuna salad, buttered veggies, salad dressings (even the bottled ones with fewer than 1 carb per TBS).
--Eat only when you are hungry. This is a hard one for me, because eating is social as well as physical. But skipping lunch is a strategy that works pretty well for me when I am LC and not hungry. Do not snack. Even on low-carb stuff.
--Don't concern yourself about exercise. Most LC adherents know that exercise for "calorie burning" is useless.