I did just foreplay sex with my girl friends but I left on her vagina after ejaculation and I didn't enter penis in vagina, she is still virgin, please tell me how I come to know that she is not getting pregrnant? She has her last period in end of April and she is expecting period on 20 of may, I don't have much idea about these things but please tell me how I can prevent the chances of getting my girl friend pregrant..

