At the early stage of my RA, my fingers were all curved in. I could not put them straight. The GP said if I did not get treatment immediately, my fingers would get worse.
During my treatment, I used to force my fingers to straighten and sat on them as much as I could. After many months, I finally could straighten my fingers but they were still not flexible yet as I had to force to straighten them and force to bend them. However, I was happy with the great improvement. I then continue to sit on them and bent them by forcing them to close against floor or chair.
In addition, I also bent my fingers outwards so that they could be curved outward to be more flexible as normal. To close them all together, it took me months too by forcing them together using many ways.
As you can see now, my fingers are very flexible. The important point here is, never give up and find ways to work on your joints. You will see result after months of trying. I hope my experience can help someone who is facing the same problem.