Super late I know but my stutter was incredibly severe. I was breathing with my shoulders, couldn't get the words out, gasping for air, blocking etc etc etc. I tried it all as a kid, but the only thing that "worked" was puberty. My voice never broke but it did just drop over one weekend and after that I didn't really stutter anymore. It does still sometimes show up when I'm really anxious though but it's not severe, just a little stumbly.