Missed periods and the role of the penis in conception

I have all the classic before period symptoms, increased appetite, cravings, increased tiredness, more acne. Yet, all of a sudden, they stopped.It's like I had a period that never happened. My acne subsided, my cravings gone. I'm worried I may be pregnant or my late period is due to stress. I have been through some stress lately. Around 2 weeks ago I was fooling around with some guy but we never had sex. I masturbated him and he performed cunnilingus on me. I know this may sound irrational, but is it possible that when I washed his sperm off my chest, it got into me? I looked up the possible early pregnancy symptoms and I have no signs besides those listed above. It's also strange as once I have more acne, my period is bound to come soon. But now, it subsided and I feel as though I had my period but it never happened. This is the first time it's happened to me.