How can i convince my parents?

im 15 all i have ever asked for is a facial piercing i got it.(because it was my 15th birthday) i didn't ask for a quince im mexican and its traditional i rather have that saved for collage.And have normal grades not bad not perfection but fair enough. i know this guy ever since i was in second grade i liked him he did too but my parents rules always came before we were little kids back then but now im feeling it its not a game i have to focus but i also have feelings i am never out i am never hanging out with friends im good but i want a little more freedom i have asked but they dont care to them its all about school. what should i do