How to know when you’ve found the one

Okay so I’m 18 and i’ve been with my boyfriend for nearly a year and I’ve literally never been or felt so happy! Sounds cringe but he is literally my world and I wanna be with him forever. I’m scared to tell him that because I’m not sure if it sounds too full on. Is it weird to feel that you wanna be with someone forever even though you’re still so young. Ik that it’s still very early days but I really do feel that he is the one. What are people’s opinions on when you think you’ve found the one?