How can you tell if a guy likes you or just playing with your emotions?

there is this boy that was in my cl last year and he would once in a blue moon talk to me or ask me questions. we also have the same homeroom which is our next cl and while i am waiting for a friend before walking to homeroom he would always ask me if i was going to homeroom or not. i would always tell him yes then he would walk away. one day wen i was walking to homeroom by myself he yelled and called me to wait for him so i waited and we walked to homeroom together. this year in homeroom he barely speaks to me even though we sit next to each other. another day i caught him staring at me but then he looked away. and whenever i see him he would always smile or say hi. i really like him but i am sooo confused. do you think he likes me? what shoud i do bacause i am a very shy girl?