Saying I love you

So me and my BF have been together officially for four months, 6 since we have been seeing each other. He's 21 and I'm 20. We hadn't yet said I love you to each other and to me it's a big deal saying those words so I've been waiting for the right moment. So today i don't even know why I did this but I blurted it out during sex. He said it back but neither of us brought it. What do you guys think about this? Should I wait for him to bring it up or am I just overthinking again lol. Sorry for the grammar my English isn't great.