If you're healthy and have regular ovulations/periods, then you have about a 15-20% chance of becoming pregnant every month. You only ovulate for about 24 hours (which is the only time you can conceive) so chances are pretty low if you weren't trying to get pregnant. Keep in mind that sperm can live inside of you for a few days though.
For future reference, the average ovulation time is about two weeks after your period starts... so next time, make sure that if you're not using protection, that you don't do it around that time!
Anytime you have unprotected sex there is a chance of getting pregnant. Why take a chance--condoms are usually readily available at clinics or can be purchased at drug stores without any kind of alarms going off or spot lights landing on you as you pay for them. If you are old enough to be having sex then you are old enough to take the responsibility of protecting yourself from unwanted pregnancy or STDs.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.