hey I'm also 17 and have had a stutter for pretty much as long as I can remember too, its not as bad as it once was mostly because I found ways around it. My advice is to try and recognize a pattern in your stuttering to find out if there are any particular letters or sounds you struggle to say and either use another word (building up a good vocabulary is helpful), or add a word in front of it to have it come off easier. A good example of this is using the word "like" in front of a word you know you're going to struggle to say, I use "like" because it's a word I've never had any trouble saying but there might be better options for you. I understand saying "like" a lot sounds corny but with time you should be able to find other words that work just as well. I was also given the same BS advice of "just slow down" and agree that it can be incredibly frustrating when you know what you want to say, but for some illogical reason you just can't get it out. I've found that thinking about the word before saying it can help and after a while it sort of becomes second nature and while none of these are perfect solutions, they can still help you on a day to day basis. The most important thing to me is just accepting you have a stutter and taking it for what it is rather than dwelling on it in self-pity, it's part of who you are in the same way everyone is riddled with imperfections.