what is love

Hey ladies! I need your help! Alright so, my lovely boyfriend and I have been dating for over a month now. Not that long but he is by far the best relationship I have ever had (considering my only other relationship was with a cheater). We don't live around the corner from each other but we see each other a lot. We've been having sex since the first date. I don't regret that. Losing my virginity to him wasn't that big of a deal to me. He has only previously had sex with one other girl. So both of us don't have much experience. Oh by the way I'm 17 and he's 19 (I turn 18 in three days). I saw him yesterday. And we had sex obviously. And in the middle of sex, I meant to tell him "I love it when you do that" but instead it came out of my mouth like "I love you" so I quickly added "when you do that" after. He didn't say anything about it. So I'm thinking he didn't notice. I literally did not mean to tell him I loved him in the middle of sex that's like the worst time to say that for the first time. It just slipped out. Since I really don't have that much experience, I know that I'm not really sure how love feels. I don't want to tell him that until I know I mean it. The first "I love you" is more of a big deal to me than sex honestly. I don't know why. I'm not 100% positive but I'm pretty sure that he's never told a girl that he loves her.  And I've never said it either. I know I could just be caught up in the honeymoon phase of the relationship. But he is very special to me. I trust him and he trusts me and we are open and honest about everything. Plus we're very physically attracted to each other. He's so funny and we get along so well. I think he's so beautiful 😍 So I guess my question here is how early is too early to say I love you? When is a good/bad time to mention it? And what do you do if (heaven forbid) he doesn't say it back?