My girlfriend and i had sex about 6 days ago, and it was unprotected. she took the plan b pill 2 days after, and started bleeding heavy with slight brown today. her period ended 8 days ago. could she be pregnant?

Unlikely: Irregular bleeding after taking plan B is actually fairly common. Between 10 - 20 percent of all women who take emergency contraception will have some irregular bleeding. If you take it within 72 hours after you've had unprotected sex, Plan B can reduce the risk of pregnancy by up to 89%. If you take it within 24 hours, it is about 95% effective. You were in the safe zone.