Theres this girl im interested in had some prolong eye contact.?

Ok theres this girl i saw at my cousins house and me and her went off in a dead stare into each others eyes. And ive never really did that with a girl and ive been in a good amount of bf gf relationships but i dont know why i did that. And the next time i saw her she looked me up and down 2 times and i had my shirt off the second time and yes i have a 6 pack. But i didnt speak because i feel uncomfortable talking and flirting with a girl i like around family. And she hangs out and lives next door to my cousin. So is she interested in me? And what does it mean when we go into a deep look in each others eyes like that for a good period of time? And should i hang out with her? And why is she on my mind all the time and i havnt even really meet. Also she alrdy knows i think she is cute so my aunt has told her lol but i didnt mind that she told her but please answer why she wont leave my mind for nothing i keep thinking of her. And please keep in mind what ive said ive never actually thought of a girl like this. And the reason why i didnt speak and i think she didnt either was because my family was around and that makes me somewhat uncomfortable to flirt and talk with a girl i like and i think she was uncomfortable to because they were around. So if she likes me alot would it be ok to go on and tell her i like her maybe after i have a good conversation with her? And please tell me why you think i feel this way towards her. And do you think im on her mind? And im 16 yes young but ive been in a few relationships so. And if my cousin isnt there this girl lives next door to my aunts should i go to her house and ask her to hang out is that a good idea? Please comment.