How do i tell if a guy has lost interest?

theres this guy at school that i like and he is in 11th grade and im in 10th. i met him about 3 wks ago when we both worked tech for a band compitition (which we won!!!) when he 1st found out i liked him he met me after every cl and he would talk to me untill he was late to cl. but now i usually only see him before school starts for like 5 min. do you think he has lost interest?? what can i do get him interested again. i really like him and ive nvr been kissed b4 but i think he mght be the one but onloy if he still wants to.