Is there a slight chance?

So I'm a 15 year old, bisexual girl. I am completely head over heels in love with one of my closest female friends. I genuinely think it's impossible to feel stronger emotion than I do for her. She says she is straight, but I know a lot about non-verbal communion and body language, and so far, the signals she give off say that she's attracted to me physically and emotionally. She often says things to me that could be interpreted as flirtation, but I'm afraid my love for her clouds my judgment. She trusts me more than anyone else, she specifically approaches me when in need of help or advice, we often have awkward moments when it seems like we're about to kiss but never do. However, we can be inseparable one day and the next day, she refuses to make rye contact, and shuns away any physical contact that she'd usually be ok with. She also talks about a boy that she's interested in a lot when we text. But when she's in my company, she says that she's going off him and we always seem to drift away from other people and spend time alone. Do you think it sounds like there is any chance that she could like me back? She is moving school soon, and once, she asked me if id continue a relationship with someone if they moved away. She told me that she's planning on telling the person she likes how she feel before she moves, but she says that she likes that guy. Shall I tell her my true feelings before she leaves? Or are the chances that she feels the same against me?

Hey Staying - I wouldn't screw up a good friendship with sex. Often times it ruins the relationship and you can never go back. Stay friends and if she decides she wants to try she will let you know because if you stay friends she will have a reason to stay in touch for moral support so maybe later...who knows?