Did he wear a condom? being that you had sex a week ago there is not much you can do to prevent pregnancy now. I suggest you start taking birth control pill and always make sure he wears protection as you can not only get pregnant but diseases as well.
i suggest you take the emergency contraceptive pill if its happened recently i've had condom accidents and have had to use it twice, and just to be sure i bought a pregnancy test. if your a bit embarrised about buying them i got my boyfriend to so maybe have a talk to him or if you feel comfortable one of your parents/guardians to seeif they can help you out
i got preg from pre c ome , so you are at risk . its too late to stop it now you should have had the morning after pill wich can be taken up to 72 hrs after but sooner the better .your only thing now it to test if you are late but stress can make you late and id say you will stress about this so test anyway to be sure and get birth control (for next time ) and dont forget condoms to prevent stds , i would also get checked for std with your doc in case he gave you anything nasty . good luck x x
you can get pregnant from pre *** however its not common. i dont think taking birth control would make it so you dont become pregnant because you would already be pregnant if you are. the only way to know if your pregnant is to test after a missed period.