The best thing you can do is to start working out and slowly cut on eating unhealthy food. Even though it might not help your stutter, it will make you feel better mentally. Btw I stutter as well, i was kinda overweight in primary school, i was bullied, and had a depression episode in middle school but i got over it. I managed to stop overthinking my stutter, my defects and all that stuff. Trust me, the best thing you can do is just stop caring. Start living your life cause, "carpe diem". Ofc sometimes ive got some negative thoughts about my stutter and how i cant do certain things, i still compare myself to other fluent people. But then comes one last thought - im wasting my time. Life is too short for analazing everything you do. It is actions that count, not the results. Even when you stuttered in front of 200 people, it didnt matter. You DID it. Thats a win. Stutters happen.