You could have shocked him, and he had no idea how to react, but to me it seems like he doesn't feel the same.. He didn't smile? Hmm. Just said ok and looked away!? Not a good sign. but looking at your profile picture..you look 12.. stop confessing love and enjoy your youth. plenty time of " love stuff.
Well if he says okay and he does like you and you know he does he's possibly just nervous to say it back to you. But if he doesn't like you then it just means he doesn't love you back. But next time I wouldn't say I love you unless you're absolutely 100% sure he likes you too. And also you should probably be "talking" to the guy as in bf gf type thing before you say I love you because love is a strong word.
it could be that he's not ready for such a serious relationship that could come after saying "I love you". If he didn't like you at all, then he would have just left. He's probably just worried that he's going to say it, then realize that maybe it isn't true and risk hurting you. Give him some time and maybe he'll decide to say it back.
maybe he just isn't ready to say it to you.... actions speak louder than words.. does he show and act like he loves you, that is the real question... Men have issues with that word "love" even if they do love you, it sometimes takes them more time to actually say those words out loud...
It means he's dumbfounded and doesn't know what to say at this time. Those are your feelings that you expressed and he doesn't have to reciprocate the same back. He acknowledged that you said it. Let it go and when he feels the same as you he will say so, don't be in such a hurry . Some guys fall quickly some take time.