I have a stutter, and have for years. i struggle with h's, t's and s's the most. what could this be a sign of?

Needing evaluation: In America, each public school district is responsible for evaluating any child in its service area, and helping that child succeed in school. That said, by the time a student is in high school, schools seem much less interested in providing speech evaluations and therapy. Go get both separate evaluations: free one by the school speech person, and one by an outside speech pathologist (not free).