I had sex once with my boyfriend. He wore protection and didn't finish. I know for a fact the condom didn't break. I have gotten my period since, so I just assumed that i'm not pregnant. But the last few months I have been super nauseated, I have had major mood swings, headaches, pain, cravings, and I have to pee every hour. Is there a chance I could be pregnant even though we used protection and he didn't even finish??