Missed lo loestrin pill on thu. (remembered fri. but only took one) had unprotected sex fri., but followed up with plan b. possible that i'm pregnant?

Possible: Anytime you have unprotected sex, there is a possibility of pregnancy. People are not as predictable as we might like and both sperm and egg have been known to be viable longer than expected. Always use condoms for std protection and another effective birth control method when you have sex, if being a parent is not something you want at this time!