I think the card you have sounds perfectly fine. "Someone special" lets him know just how you feel about him- that he's someone special. It doesn't necessarily have the label of "boyfriend," but it doesn't have to. As long as what is in it conveys meaning you feel, then that's what matters. I am sure that he will like the card and, as Ellie said, if you're truly in doubt, you could go to another store and look at cards there for more variety. I think you'll be fine with the one you have, though.