Michelle,
If you didn't take your birth control for a week, then it is possible that you might be pregnant. The symptoms you are describing could be early
pregnancy symptoms, but don't panic yet. You could take a test now, but it is probably better to wait until your period is actually due and you are late. If taken too early a test might register negative when it is really positive if the levels of HCG hormone are too low to register. My advice would be to try not to stress too much (I know easier said than done), and wait and see if your period starts on time. If you are more than a week late I would take a home pregnancy test to find out for sure. Good luck.
Kate