possibly pregnant?

Hi guys I really need your help and opinions. I am 19 years old and I have been on the pill for 14 months. If I ever missed a pill I always took 2 the next day but 99% of the time I have always taken the pill on time every day. Two weekends ago my bf and I had sex one morning with protection around 10 and two hours later had sex again but without a condom. He pulled out  about 30 seconds before he was gonna finish. We can't remember if he went to the bathroom after the first time we had sex. This past week I have been extremelystressed at school and haven't been drinking a lot but when I do even if my bladder isn't full I have to pee right away and I can barely hold it in. I read stress can cause you to pee a lot but frequent urination is a sign of pregnancy. Do you think I could be pregnant?