Update little sister having sex

she admitted to having sex three times. The first time was unprotected with a guy named DJ and the other two were protected and with DJ's friends (I'm assuming at different times. I think she may have had sex more than she telling me but I told her that if she continued to do this it could have a bad impact on the rest of her life. She wants me to get her a pregnancy test just in case, I don't helive she is pregnant because she didn't start her period until October 22 (something like that maybe 20) in 2014 and from what she told me they had sec with him in the Summer. She was kind of sad about the rumors and that she would stop because she dosnt want a baby or STDs or anything like that. I hope she talks to me more when stuff like this happens, thanks again for the advice!