What does it mean when a girl tells you i want to be your sister at this point in time?

Ok so this girl and i have known each other for a half year and it has bee up and down. In the beginning things were going good but as time went on stress and school kinda ruined things. Beginning of the year i asked her out and she said she wasnt ready for a guy in her life but i asked her to be honest and say what she thought of me and she said she felt we were more than friends. I then asked her if she wants to date after school ended and she basically told me this: She has been stopping herself from liking me cuz she thinks it wouldnt work out cuz currently im one of her closest friends & shes scared if it dont work out she will lose me. Also saying the relationship would end in badly cuz thats what all the signs point too but she didnt give any rationale explanation. So then she finally said i wanna be your sister. Thats all I feel comfortable being right now. So she starts dating other guy friends but not me cuz of reasons just said. Is this rationale fear? Should i trust her gut and say well if its meant to be it will happen in the future or is she giving me BS and this is the friend zone? She said shes not giving me BS but who ever admits that? So basically i told her lets be casual friends now and cut her off, but i want to know would i be wasting my time to try and see if there is something there or just forget it and move on. I wouldnt mind being friends but if she cant be honest with me and tell me i only see you as a friend straight up then how can she be a good friend? Let me know if im off on this or whats up.