you normally only ovlulate between 11 and 14 days after your period, the chances are not likely; but there is always that chance that your system works differently to others. Please, you do not want to fall pregnant at your age, so please always use protection because then you wont be left with this kind of stress every time you have sex.
A woman can get pregnant any time of the month. You have to use protection every single time, no matter what time of the month it is. You can take a pregnancy test a few days before your next period is supposed to start. If it comes back negative but you don't get your period take another one.