More than age, it's a thing of mindset and how you view your stutter. Getting older doesn't necessarily mean your stutter will get better unless you take steps to make it better. By that, I don't mean curative therapy. That doesn't work most of the times. Didn't for me, at least. I'm 23F. The only way I've been able to take control of my life as a stutterer is by throwing myself in a situation I feared and just speaking up, pretending I dont care what others think and what I say is more important than how I say it. Yes, it's daunting and I cringed at myself the first few times I did it but then I saw people were more interested in what I said rather than how I said it. I have also been in situations where my speech presentation was important and practicing in spaces where it wasn't important gave me some confidence and I could stutter WITH confidence. A few weeks ago, I sat for a job interview and stuttered. The recruiter said my stutter is a disadvantage but I spoke up for myself and told him exactly why he's wrong in thinking that. I got the job. You can't make your stutter go away. Sorry to break it to you but once a stutterer, always a stutterer. You just have to grow confident in it and decrease your reactivity. Most often it's our body language of nervousness and fear while speaking that others mirror and get the audacity to mock you. I'm not saying there won't be people who'll mock you when you're confident but at least, you'll have it in yourself to tell them off. For me, this has been the only way. Also, read about dysfluency social theory rather than just medical curative self help books. The medical approach will tell you that you're defective but the social model will instill confidence in you.