Kinda sounds like shes not interested..a girl who wants to get to know you will make sure theres an opportunity for it. Not run away every chance she gets. Might as well ask her straight up and find out. Eh but what do I know..
If you keep wasting everyday at attempting to find her alone you will lose all hope and whatever interest is there... Hop on that and LOCK.IT.DOWN! [ame=http://www.youtube.com/watch?v=Cd6A5PNvY4A]YouTube - The Waterboy- You Can do it All Night Long[/ame]
I'd just walk up to her, regardless if her friend is with her, and ask her if she wants to chill with you. Phone's are only a thing for emergency's If you can ask the shit you want to ask in person, then do that. Texting makes things more complicated.