He does this and that but what does it all mean..?

He treats me sooo great but he won't tell me whether he likes me or not so how am i suppose to know? He looks at me alot and he flirts all the time and he told his friend a while back that i was his gf and he came to my party and we had alot of cute moments where like we were in my room alone and we just talked. He always chooses me to be on his team when we play manhunt or football. His sis told me he likes me but im not sure. We go to school together every day and we talk alot and tell each other everything he's like my guy best friend but i really like him and i flirt alot too but i just can't tell whether he likes me back or not