Age difference between me & my bf. idk how i should tell me parents?

ok so i'm 12 and my bf is 15. idk hwo i should go about telling my parents. i'm turning 13 in less the na month so its onlii a 2 year differnce. but i'm not sure my mom will be soo happy about it. hes a super nice guy and hes everything i could ever ask for. plzz help i wanna make this work out!!!