Discomfort while playing piano. What am I doing wrong?

I saw a doctor about three months ago because of tingling and numbness in my hands, due to improper playing. She said that it was mild cts and tendinitis. It went away in a few weeks, and I bought a new bench to remedy my posture; it's still difficult to get into a comfortable position. I've made countless adjustments to bench height and distance from the piano, and I can't relax my hands any more. I've made sure to keep my arms about parallel to the floor and my elbows just above the keys. Nothing seems to be working. When I'm playing, should I be in a position so that my wrists are in their natural shape without much conscious effort by me to keep them there? I'm running out of ideas.