You have to stand up for yourself! People don't care about, if a sentence takes longer than usual. If they make fun of you or anything else, they just suck! Speaking is the only way to learn how to speak fluently. What helped me, was starting with an exhale, so the word would flow out of my mouth while exhaling. It may sound really soft to other people, but it was the best way for me to speak. Also, if you like to sing, just on your own, you will realise that it is not possible to stutter while singing. So, if you get a melody in your speaking it can sound really nice and helps you to get comfortable! I hope you understand my English, sry for mistakes