Afraid to Take Birth Control

Hello ladies,
I need some advice. My younger sister is afraid to take birth control. When I talk to her about it she gets defensive and looks annoyed. But I know she's just scared. She's worried about her body and hormones and all of that. 
She is living with her boyfriend and they are using condoms.... However she is no position to be pregnant right now. They are both very young and knowing her BF her life would be hell if she had a child with him. I'm desperate to get her on birth control ASAP she recently moved very very  far away from me so I can't take her somewhere myself. I only can try to persuade her to take it over the phone. 
She's 18 and she's just afraid and young. Like eye rolling and all of that when we talk about it... Because she's young. Any tips on how to persuade her?