Oh I feel so sorry for you. I am 17 and also have been stuttering my whole life. Though it got significantly better with speech therapy (I really recommend this, please try to convince your parents), I still get this nervous feeling whenever I know I have to speak. I enjoy being social but this fear keeps holding me back. It's really tough to control, I know exactly how you're feeling. Best tips I can give you is to try for yourself to read aloud, from a book or just some story on reddit, and practice speaking. Also, try watching your breathing, I know from my experience that if I get my breathing under control, it makes matters a lot easier, hang on buddy.