How do you know when you're in love?

how do you know when you love someone? There’s someone really special to me and no matter how hard I try or how long I stay away from him for, I can’t seem to stop thinking about him. I’ve got to the point where i’m having dreams about him (sounds stalkerish but I can’t help it) and when i’m not with him i want to be. I actualy miss him. I’ll stare out the car window and daydream about being with him and everytime I do see him or have a conversation with him, all I want to do is kiss him. Am I in love with him? I think I might be.