I am still breastfeeding. I took Plan B on friday and sex on saturday and condom broke. Can I still get pregnant?

Possible. Anytime you have unprotected sex, there is a possibility of pregnancy. Breast feeding is not a reliable birth control and condoms are not 100% (about 85% if used perfectly). 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!