He hasn’t said I love you

I’ve been with my bf for 9 months now. It’s both of our first relationship. We’re 19. Everything about it is perfect. He hasn’t said I love you yet though! I really want him to! I know it’s 2019 and I could say it first but I want him to! Why hasn’t he?! At what point should I start to get worried? I think he’s really perfect for me in every way. I know how naive that sounds but I feel as though we have a very mature relationship. But what’s up with the lack of those three words?!