You say you're not interested in gaining weight. But you want to gain mass?

Well, gaining mass means gaining weight. And sometimes, yes, there's going to be a little fat gain there too. It's just something you gotta deal with.

But, not to sound demeaning (even though it probably comes off that way ) I'm 8 inches shorter than you. And I'm 8 pounds heavier. Really, I think it would be in your best interest to cut back on some of the cardio and work towards building some muscle mass. Gathering from your height and weight, you've got to be pretty darn lean right now, so the best thing to do is to put some size on and go from there.

As far as supplements, get some whey protein, multi vitamins, and fish oils. That's really all you need. And especially with you being so young, you're really not anywhere near the stage of needing to supplement your diet.