GUYS! i need your advice?

he is shy in cl and very quiet. anyways, i gave him my number about a month ago, and when i gave it to him, he kinda laughed, stared at my number for a few seconds, and put it in his pocket. i gave him my number cause he seemed too shy to give it to me. like whenever we talk his whole face gets red and his leg shakes. it sounds like his voice shakes a little also. the problem is, he never called me. he is always texting on his phone, so i dont know if he has a gf, although he has mentioned NOTHING about having a gf, like on his birthday, he just hung out with friends, and when i ask him what he does over the weekends, he says he just chilled at home and worked. and the other day some girl joked to him saying "imagine if you and her (meaning me) had " and he laughed and got really red again. i know body language can sometimes say a lot, if he sits behind me he will lean on his desk closer to me, and when he sat behind another chick he didnt do that. should i cont. flirting? hes 21