I have back problems as well. I started by visiting "Relax the Back" store. They have zero gravity chairs and ones designed specifically to address bad backs. I found the seat below. It can be purchased elsewhere.
From experimenting I found the McCarthy SacroEase Seat. It is made for cars, but works great on couches or chairs. The arch for your back is adjustable... in degree and location. It cost a lot because the actual metal is bendable. So you can get it to fit just right.
I have three, one in my library, listening chair, and in the home theater. Took some work, but they all now help my back... so when I get up I can walk more easily... pain free.
https://www.amazon.com/dp/B0CYF58KZQ?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_2
Yes, I know they are currently out of stock. But this gives all the details.