Given your ages and the weight difference, you don't sound like a candidate for a transfer belt to me now that I think aboutit. But maybe look into the riser. No doctor's note or prescription needed.
And some home safety evaluation help is definitely in order before the two of you have a crisis that lands one of you in the hospital. I do not say this casually, I have seen it happen too much!
Ginger's suggestion to make some notes is a great one.
Sue