I'm worried about my best friend getting pregnant and she won't listen?

I've known her for awhile were close like sisters we been close since kindergarten. She is the type of female who isn't ready for no baby even though she doesn't wanna tell me I feel like she wants one she just doesn't wanna say it. I keep telling her if u keep having sex ur gonna get pregnant. She's been having unprotected sex with her boyfriend since March and she always tells me if he cums inside me I'm not gonna get pregnant I don't think I can have kids anyways he has came inside of her like almost everyday or sometimes once a week well that's what she has told me until now she's been having a lot of unprotected sex with her boyfriend I'm like oh my godd. She thinks she can't have any kids because she had chlamydia before but was treated and she is underweight. So she basically thinks every time her boyfriend cums inside of her it's okay I'm like really 😒 for one she doesn't like condoms plus she's allergic to latex idk why she won't buy any and I told her about birth control she said no because she thinks it's gonna mess up your fertility in the future plus she hates taking pills. I'm not doing this to control her I just wanna help her because I care I know I'm not her mother but I was pregnant before at a young age lost it but I wasn't ready too be a mom. She has goals in life her family is against her getting pregnant plus she's only 18 I'm only on her head because I care. Ugh I don't know what to do😔