friendship help

by Megan
(Scotland )

me and my friend have been like sisters for 5 years now but i`m 14 and she will be 18 in April our age difference has never mattered before she was always there for me no matter what but for the last 4 moths shes been ignoring me at first i thought it was because she was stressed but her exams are over now and she still wont talk to me.

she promised me that if there was a problem she would tell me but she hasn't. i`m worried because she used to always stick up for me and protect me but she leaves the school next year and i don't know how to stick up for myself i wanted to keep in contact with her when she left school but she hasn't given me her new mobile number and whenever i ask she just says "oh i will give you it later" but never does. i`m worried that i have done something wrong and its making me upset and depressed what can i do ???