Would it make sense to do this with a licensed professional who can guide you? I already see a flaw with you focusing on breathing when in general stuttering rarely has anything to do with breathing. https://stutteringtherapyresources.com/blogs/blog/its-almost-never-breathing?srsltid=AfmBOopzJ1cnMAEO1vw_wP50Tk9vp5gfqV4ySc-75ac0xEPyMrrAThVo