You’re doing well man! You’re self-directed enough to come on Reddit and ask questions. Keep being inquisitive about yourself like you are now. Ask as many questions as you can to anyone that is knowledgeable about anything. Especially seek older folk and ask them about confidence, about speaking to others under pressure; about not valuing non-constructive criticism. Watch interviews of famous people that you wanna be like, and note what they say. Eventually you will build yourself up a nice set of ideals and values, which will help your confidence and overall life quality. Keep going bro. Stuttering forces us to get to know ourselves. And forces us to desensitize ourselves to the opinions of others. A good thing for you to do might also be to join a sport at your school. It’s a good way to excel and gain confidence in something that isn’t speech related, but winning and self-improvement can help your speech. Also try to discern if these people at your school are good friends that are just joking with you, or are actually trying to put you down. How about calmly try asking them to not making fun of your stutter? But don’t do it defensively OR hesitantly because then they might use this type of reaction as a reason to keep picking on you. Just ask them assertively but like your relaxed enough that you’re not worried if they don’t stop picking on you. You’ll just find new friends if they don’t stop. Or just laugh along with them if they laugh at you; that’s another option.