I have fallen in love with this girl and I don't even know her help me please.?

Ok theres this girl i saw at my cousins house and my cousin is a girl btw. And when we first saw each other we went off in a dead stare into each others eyes i felt like i connected with her and when her and my cousin drove off on there four wheeler she looked back just to look me in my eyes. Then about a week later i saw her again this time i was swimming and had my shirt off and yes i have a 6 pack i caught her looking me up and down when i looked back she looked away real fast then i caught her no less than 10 seconds later looking me up and down this time i looked back she didnt turn her head she got lost in my eyes and grabbed her arm. Then my aunt caught us looking at each other and she asked me after she was gone she cute isnt she dont you think i said yes very. then i said you can tell her that if you want to she said oh i will. Then when she told her i was already gone and i asked my aunt what did she do when she found out? my aunt said she just looked at her for about 10 15 secs with no expression on her face what does that mean? Please help me here. is she interested in me at all? And P.S. my sister txted me to death about who i liked i told her she said she wanted to become friends with her i said ok she wants to find out for me if she likes me or not and i told her i can find out on my own. And btw when i found out what she did i left her my number was that a bad idea to leave the girl my number? And is it a bad idea to let my sister just find out if she has any interest in me or not by just telling me things like if she thinks I'm cute and what not not actually talk about me just she if this girl does have interest in me or not and I do trust my sister so. Please comment.