I have fibromyalgia and holding a book started causing too much pain. Now I use a Kindle with a Book Seat. It's like a little bean bag chair with a clear bumper to hold the book/ebook in place.
https://www.amazon.com/Book-Seat-Holder-Travel-Pillow/dp/B0049VCA04
It's a book seat. Possibly Not correctly assembled. The one in my link has a transparent part where yours has wood.
https://www.amazon.com/Book-Seat-Holder-Travel-Pillow/dp/B0049VCA04
You can put a book in it so it rests nicely on your lap. I use it for my ipad, i really like it. Here’s a link to amazon which has a picture of how it works. amazon
Have you tried anything like this? It’s on my amazon wish list but is a bit pricey. The Book Seat - Book Holder and Travel Pillow - Red https://www.amazon.com/dp/B0049VCA04/ref=cm_sw_r_cp_api_i_hKLpCbDWRT3XE