My cheerleading skirt...?

Ok so im a freshman and i made the jv cheerkeading squad. we get skirts from like peope that graduated and the skirt i got is too short. it is supposed to be pulled up to your belly on so that it goes over your right. but if i do that then it is waaaaay short, like it barely covers my . but if i pull it down so it's long enough then it sticks out to a pint in the back can i get lenght added to the skirt or caould i get it added to the top? i dont know what to go. we have an alterations lady but i have to convince my mom. is there anything i can do about my skirt???????????? pleased and thank you(: