Best friend to Girlfriend?

my friend "Kathy" and i have been friends since the 7th grade, and now we are Sopres in high school. we met during a Spanish cl when i asked for help on the homework. later in the year, we had to dance in a mock Quince. i asked Kathy. she said yes, but only if i wouldn't think of it as a date. i went and had some fun, but i really dislike dancing. anyways, some years later we hang out whenever we can, like at school football games on friday. i don't really get to see her as much as i would like to. and we only have one cl together in school. when our homecoming dance came around, i asked her to go with me. she said no. now i feel like i really screwed up our friendship, and that i'll never have a chance at a relationship with her. what can i do to get her to actually consider dating me, or to get rid of the awkwardness that i created when i asked her to the dance?