Thanks for your question and concern, I can very well understand that you are concerned about the possible reasons for pregnancy. Pregnancy is a matter of concern after sex and it is very important that you are taking extra care during sex. Even sometimes mistakes can happen and a small mistake can give you a big result that is why it is advisable to go for a safe sex. Definitely it is advisable to have a backup contraceptive method in the starting month of your oral contraceptives within the first 2 weeks. It might be possible that you can be pregnant but as you told me before and you are sure of that there was no ejaculation your chances of becoming pregnant can be nil. But still I would advise you that you should continue with your contraceptives method and then wait and see whether you have your menses occurring at the end of the cycle. With this you can test yourself. If your menses are not occurring at the end of your cycle please do not panic. There might be a possibility that your oral contraceptives could result in irregularities in your menses. The chances of Knoppix may or may not be are there as it all depend on the test.