Do not take anything that has any short term effect on hormones that affects confidence and fluency. Work on yourself, as complex as it is, try to workout whether your stutter is primarily induced by low confidence/self esteem e.g., can you speak fluently to yourself or to animals? Work on this. Go gym, eat/sleep well etc. In other words, train yourself to not give a fuck what people think of you, because in reality, they don’t. Try to expose yourself to situations where you are speaking to multiple people. Try mindfulness and train yourself to think in the present and not the past. Then try therapy, any speech therapist that has a deep understanding of psychology. I’m also 22, I’ve stuttered my whole life, over the past year of doing this I have infact noticed a slight improvement (without therapy). Remember that it’s no short road though. And don’t let it stop you from doing anything that’s going to benefit you later down the road. Good luck