I gave my boyfriend a blow job, he ejaculated and then urinated. Later that evening, we wanted to see what it would feel like. So I briefly gave him oral to get him hard. He then penetrated me momentarily, and removed. He was not near ejaculation, and he went and ejaculated in the bathroom and urinated again. That was the end of that. My period starts on the 15th-17th of every month fairly regularly. This occurred the evening of the 27th. I took Plan B 40 hours later. I am incredible stressed and concerned that I may be pregnant. What are my chances?