I had the same problem, and I really only fixed it by getting a different mouse. You can look up different mouse reviews, the only mouse reviewer I knew was RocketJumpNinja, but there are probably others these days. He had lots of comparison videos which were helpful in determining which would work best for me and my large hands. (I ended up with the Corsair Ironclaw wired. Not the best mouse shape, but it works well enough).
They are good, but chronically underfunded, and we need to copy virtually everything the European version of the FDA has banned.