how about practi9ce just octaves, to mkae your octaves better? Try czerny octave studies. And you will become a nu Horowitz 
I’m actually fairly surprised at how well the Hannon C maj octave excersize works.
btw, something my teacher told me that seems like a really good idea
when tired of playing piano, bounce a tennis ball close to a surface, its like playing octaves, but more so with the wrist.
A great excersize.
play them fast