Oooooh my god, why are you kids so stupid!?
Firstly, it's been a week. What makes her think she's pregnant? Missed period? Cramps? Paranoia cause you kids didn't use protection...
Second, WHY did you not use protection? Do you want a baby?
Keep this little slip up to yourself until you know whether or not she's pregnant. If she is pregnant, well obviously you must tell both her & your parents and then figure out what you're gonna do.
If she is not pregnant (fingers crossed) then for the love of god USE A CONDOM!!!!! Much cheaper than babies!!!