On bc but switched brands this month. boyfriend and i had sex w/o condom and i'm worried that switching brands makes me at risk of pregnancy. plan b?

Unlikely: If you did not miss any pills in your regular schedule, it is unlikely that just changing brands would increase your chances of becoming pregnant.

OK: If you haven't missed any days, Switching brands should not make you more likely to get pregnant. Plan B contains a high dose of what is already in your BC so it won't hurt you. But you shouldn't take Plan B more than once per month. Best wishes.