His and Her Health

hi actually am writing this mail on behalf of my girl friend. her periods usually comes on 18th of every month. this month on 2nd we had sex but i just humped for two times and we both felt painful and ttense. so iremove my pennis. and this happened on 9th of this month also. but now she didnt get her periods yet. are there any possibilities for her to become a pregnant. if so how to stop her pregnancy as we were focussong on our future. and we wil be married after 2 years. right now she is writing her exams. and she is feeling tense. could you please gimme a solution so that i will be thank ful to you. thanking you,
vamsi.