Should i be worried if my girlfriend is 4 days late? we have had sex several times without a condom at the start (max 10 minutes) then put one on i always finish outside of her too never inside of her and in the condom i'm 18 so it's kinda scary

Might be pregnant: She could certainly be pregnant. Condoms are only effective if you actually use them. Even the pre-ejaculate contains sperm; she could get pregnant even if you ejaculate into the condom because small amounts of semen come out during sex. I would recommend using TWO forms of birth control during sex (i.e. the pill AND a condom).