My girlfriend has been off the depo-provera shot for 5 months and the condom slipped off she took plan b but she might be ovaluting will it still work?

Condoms: are only about 90 percent effective. Plan B is effective, but I dont recommend using it as a contraceptive. It is for emergencies. If you and your girlfriend dont want to create a baby, I would not rely on Plan B or condoms alone. She should get on another form of birth control that has a higher contraceptive rates. AND use condoms as well.