Girl help needed...Ex help needed... Same thing D:?

I'm 14 and need some real advice, I'm in to this girl named *******. She is in my Spanish class only but when were around each other she's really nice to me and seems interested in me but not enough for my satisfaction, Oh yeah she is also my ex from last year. But back to the topic, She always goes really close to me to do weird things like count the stripes on my stripes on my shirt or how long my arms are... I like being around her but uh... Its just a lil weird interacting that way. My phone got changed so I don't have her number from back last year so should I approach and ask for her phone number or does it sound like she even likes me?

P.S. I talked to her best friend about and she said that if I asked her out, she would kill me. WTF does that mean?