I feel like I should be doing more

That's a good sign of recovery but please try and ignore it! You really do need not to do anything other than getting well. This is a major operation and lots of rest is the best way to heal, take it from one who's been there! Enjoy having the time to read, listen to music, whatever you enjoy doing and that daily life doesn't usually allow you much time for.

(Sorry if I sound a bit bossy - just very concerned.)