I keep overthinking and it’s driving me mad

I keep overthinking and it’s driving me mad I have found in the last couple of years in particular I have started to overthink about my stutter and everything around it so much. I’m 17 now and I’m at the point where I don’t even want to put my hand up in class because I know I’ll stutter, probably a lot. I used to be able to put my hand up and answer questions and not care if I stuttered but my self confidence is just gone now. Back in primary school or the start of secondary school I was able to just brush off any time I stuttered or someone said anything to me about it. A few days ago I was asked to answer a question in maths and couldn’t say 8 at all and I haven’t been able to stop thinking about that. I felt really embarrassed in that moment even though this wasn’t exactly a new thing for me or anyone in the room. I’m just so fed up of it. I just want to be able to speak when I want to and not worry about it I’ll even be able to or not. I want to do so much in the future and I don’t want my stutter to get in the way of all that but, not gonna lie, I’m pretty nervous about all that.