I have a similar problem actually, except i'm a girl getting mixed messages from this guy i've had a crush on for over a year now. I'll start from the beginning..
In year 8, everyone kept urging us to go out bc we're both blonde and"suited eachother" so we did but nothing really happened other than holding hands in pe,walking home together and mutually breaking up after two weeks. In year 10 i tried messaging him a couple of times but he blanked me. These past weeks we've had more contact - he followed me on instagram, i follwed him on snapchat. Whenever i like one of his pictures, he'll like one of mine back later, and we signed eachothers shirts on our last day of year 11. So, feeling brave, i messaged him again and he replied within the hour! I was so happy but then the responding time for him gradually got longrr and longer, he hasnt replied to my message which i sent at 3 yesterday, even though he has been messaging others since then. But in his messages he is kind and funny and asks me questions back, so is he interested but really forgetful or spends forever figuring out the right thing to say, or is he trying to shake me off bc he's not interested?? Btw, i'd say he is pretty popular ( he's friends with most people but smokes weed and is slightly more subdued than his friends) but so am i (i have a good&friendly rep and got voted as prettiest girl in year 11). Could you give me some advice?