Doing exercise an not losing weight?!?

ok im 5'7" 146 an i do volley ball. right now im in a competitve volley balll camp and im STILL not losing weight! i thought id lose weight- cuz ya knoww im doing a sport an every thingg and im good at volleybal too! so please jus help mee an any way to boost metalbolism? <------ IN THOROUGH DETAIL PLEASE! ive read stuff online but its no use its like theyve never had experience or somethingg! so please help thanks<3