My girlfriend is not feeling comfortable with herself, how can I do more?

So unfortunately my girlfriend and I are in a long distance relationship so I can't physically be with her(not sexual, just need to make that clear) but she's been emotionally scarred from high school days about her looks and personality and it's just an awful situation. When I tell her she's beautiful or that her interests are amazingly awesome, she doesn't believe me and is afraid that I'll find someone better eventually, all because of being bullied all her life. I feel like I'm making it worse by keeping on reassuring her that I won't and that I don't want anyone else and there are only so many ways I can console her. Any strong advice from the ladies out there or even the men? I just want her to see herself as the beautiful, sexy, interesting woman that I see her as.