I think stuttering publicly will ironically make you seem more confident. I'm almost 21 with a pretty severe stutter and I heard this remark many times from different people. Of course it takes a lot to push yourself and actually speak in public settings, but I note that this will most likely end well for you. Sure, people will first give you a weird look and ask "What's happening to you?". But if you immediately let them know that you stutter, they will most likely back down and apologize. The way I see it, stutterers who speak in public are way way way more confident than nonstutterers who speak in public, this is what pushes me to speak publicly. (I would still get nervous though) And I don't think one can ever be "too late" to control a stutter. Notice how I said 'control' not 'fix'. You have to accept yourself as a stutterer and try your hardest to control it until it's barely noticeable in any scenario.