I need words of wisdom

My girl best friend and me were 'planning our wedding' like chocolate fountain, bouncy castle and matching dresses and other more serious stuff (we're both 15 although she's a bit older than me btw) to annoy her boyfriend in good fun. I recently made a joke about it and she said "you know that was only a joke right?" and don't get me wrong I did but I still felt kinda rejected and that made me realise I like her.

I'd always thought of her like a big sister but recently I realized I begun to love her in a different kind of way. Honestly I kind of feel a little heartbroken because:

1) she's straight and would never think of me that way.

2) my parents wouldn't approve of any kind of lesbian relationship. I even asked my mum how she would react if I got married to a girl and she said she couldn't come to the wedding or think of us as together although she'd be happy I'm happy.

3) I honestly thought I was asexual until this and now I'm suddenly realizing I'm not and it's scary.

Any advice right now would be great.