I'm a speech therapist who stutters. I've had a lot of success with helping students using a technique called breath stream management, sometimes referred to as "the breath curve." It takes a lot of practice, but I've seen it help quite a bit. It helped me when I was in college to the point where now nobody at by job even knows I stutter until I bring it up. If you're in the US, ask your parents to ask about behind evaluated for speech therapy at school. I'm not sure how it works outside the US, but depending on the state, they'll likely honor a parent request.