How do u get a guy who already likes u to talk to u...oh and by the way, ur already in love him.?

ok so, i saw this guy at a store where I went to buy something. at first i thought he was an cause he didn't tend to me right away. hate him at that point. then he comes, helps me out and its all good and then we start flirting a little but it ends right there becuase i had to leave and i get the sense that he thought i was under age and he left it at that. i'm not underage by the way, I'm 19. This was on a monday and i'm just infatuated w/him cuz he wasn't so bad and he was REALLY CUTE. so i go back on thursday, he's on the phone and i'm on mine. we don't talk cuz i didn't want to seem desperate but i could tell he was looking. turns out i really like him but i don't want to go back cuz it'll just seems desperate. and i can't take a friend with me as an excuse that he/she needs something and if i go with the excuse " i'm buying something 4some1 else" he'll just know that its cuz of him that i'm there. wat do i do? i really, really, really like him. cant stop thinking bout him