If you developed stutter not from genetics(you said none of your parents and siblings have it) then it must be environmental/psychogenic stuter.Also if you ran into decent professionals,they would be open to adult PWS as well and most of them are lending hands to [them.So](https://them.So) it seems like you haven't run into good therapists yet. Maybe you forgot the exterior reasons inducing your stutter but as a high school student,it's very impossible to catch a developmental stutter during that time. In addition stutter is not retard or disabled,just normal physiological or psychological deviations and that's all. If you can't stand stutter and wanna work out,just move for more skillful SLPs,better than just chewing over what stutter is bringing to your life and moaning about it at home.