How do I know if he likes me?

School started 3 weeks ago and the teachers were saying the names of the students that will be in their homeroom . I was called first from my homeroom list and I was thinking all along was " I hope I get MY FRIENDS in HOMEROOM THIS YEAr!" ( I got none btw) well then I looked at this guy and I was like "OH GOD I HOPE HE IS NOT WITH ME!" Next thing I knew my hr teacher called his name and I was like , SH!T! The we went to our new clroom. When she was giving us igned seats I was hoping again, I DONT WANNA SIT NEXT YO THAT DUMB@SS, but she sat him next to me! I was soo freaking mad.The thing is, I have known him since 1st grade, my mom knows his dad since they were in 3rd grade and he used to live reeeaally close to me. Iv always HATED him I couldn't stand him at all, but over these few weeks I guess iv started liking him. And he used to be really mean to me and now he's changed. He looks at me in all the cles we take together, he smiles at me , sometimes even for no reasons, when I answer something wrong in cl , he starts arguing with the teacher , trying to convince her that I'm right ( which is reeaaalllyyy funny). I used to think he was a jerk and now I'm changing my mind and think he's really sweet. :) Oh and also, the other day I was all embarresed because I thought my hair looked stupid and messes up cuz the water was shut down at my house and I saw that he kept looking at me and I thought he was just looking at me cuz he thought I looked retarded and he surprised me by saying " You look Beautiful today". Idk but I think he sort of likes me but I'm not sure. Idk why he would like me! We r completly different! He's so outgoing and I'm shy ( . Plzzz help meeeeeeeeeee!