You have my sympathy - had rheumatoid arthritis for over 10 yrs. My left hand is the worst problem - I am left handed. My hands are pretty bent - the fingers all going towards the little finger.
Good tip to learn to use the mouse with both hands. I have spring loaded scissors and the are great.
I cannot knit at all, hand sewing is not easy so I limit that. I have just worked and worked at making my machine do it all for me. The best answer is to keep on trying and trying and looking for ways to make each task easier.
Jane