No period for a year because i'm bulimic and underweight. should i be worried i'm pregnant ?

Probably not: If you are not having periods you are not ovulating and it would be very unlikely that you could become pregnant. If you are unsure take a pregnancy test. Please try to seek treatment for your bulimia to prevent long term damage to your body. Counseling and medications can help. It is important for your to find a good counselor and commit to the process. Good luck.