Hi Beryl, if you want to size up the pattern don’t worry about changing the stitch count — just change the hook size and yarn size. For bulky yarn I would probably use 4mm hook! You can also check out my detailed guide on resizing amigurumi here for more options: https://littleworldofwhimsy.com/my-foolproof-guide-to-resizing-amigurumi-no-math-required/