Can Repeated Intake Of Plan B Cause Irregular Periods?

hey. my gf has been on birth control for 2 years now. on December 25th we had sex and I may have gotten some ejaculation in her. she took plan b and got her period a few days early. then last Sunday we had sex and I ejaculated in her and she took plan b again in a 17 day span. now she is breaking out. is it possible she can be pregnant. she doesn t miss pills