Wats happening? im confused :(?

okay so i am a very very shy person..im 15 but im still not comfortable in telling my frnds bout my crushes i have NEVER even told dem bout 1crush also not even my bestest best frnds (cass n liz) i really dont know why but just cant..so heres da thing...i dont want to date nebody till when i am atleast 17 n i never even feel like saying yes to whoever asks me out.. i like a guy n i THINK he likes me back...i might be wrong ofcourse..BUT my frnds n everybody it seems thinks i like that guys best friend who i am very good friends with..i have told them a million times i ddont but nobody believes me :( a few days back i got to know liz is dating a guy...n i am like ok wateva but today i got know even cass is dating!! n now i feel soo out of place bcoz they keep toking about their guys n im just blank..today a guy asked me out.not the guy i like but a guy who i know since like forever...should i just say yes?