please help?how can i tell she doesnt want to talk?

[Bubbles]

well there is this girl who is 19 and i am 17 and i think she is beautiful,well she is sorta friends with my sister but not really,and i asked my sister if she could help me get to know her a bit,and my sister said no she doesn't want me to,my parents said i should and her dad likes me and said he doesn't mind,but she told my sister she doesn't want to get to know anyone until she is 23,so here's my problem my mates think i should as well,i want to so bad but i don't wanna stuff it up,we wave at each other and have said hi a couple of times but everytime i get a chance i freeze and cant say anything,plus i get the feeling she sorta doesn't want to talk cause she wants to stick her 23 plan thing,or is that me being paranoid?please help!!