How Safe And Sure Are Emergency Contraception Pills?

my girlfriend and i had sexual intercourse however our condom split, we rushed of to get an emergency contraception pill and that was fine... my girlfriend was due her period and expirienced it 2 days later which lasted about 5 days... we then had secual intercourse a day after and yet again a condom split which is quite weird we went to the pharmacy and she talked to a consultant he said there wont be any problems except from her next period coming 5 days to early or 5 days later so she took the emergentcy contraception pill. However 4 days after taking the second pill she began to bleed for 2 days straight and it has stopped today. we are very worried that she may be pregnant could u try shed some light on what could be going on ? thank you