I kissed and slowdanced with that boy but he didnt ask me yet.

I think -- and you can feel free to reject this if you wish -- that saying "I love you" might come under something you do after you become boyfriend and girlfriend and not before.

But okay, so it's a tiny bit backwards. That's not fatal.

There is no reason whatsoever why you cannot ask him out. Just ask.

"Sean, do you want to go to the movies?"

Or to a café or out roller blading or whatever you might want to do that you think he might enjoy, too. If he wants to be with you but doesn't specifically want to go to the movies, he'll suggest something else. So it kind of doesn't matter which thing you ask, just something light, with no pressure behind it. It's the movies, not marriage.

If he says no and offers no alternative, it's possible that he doesn't want to be with you. I'm sorry but that is sometimes a possibility. If that happens, it's all right, it's not the end of the world, and you'll know for next time. Because, believe me, this is probably not the only time you will ever, ever kiss and slow dance with a boy.

Now go ask.

You can ask:
"Hey, that time (kiss, dance, whatever) with you was great. What does it mean for us, now?"