what do you think?

Is it possible to know/feel like you're pregnant within a few days after conceiving? My boyfriend and I had unprotected sex on the last day of my fertile week and he came in me and about 2-3 days later my boobs became really sore to the point where it hurts to even touch them.. I feel a little different, but I feel like it could be PMS since my period is supposed to come on in 5days.. But I normally only get emotional the week before my cycle starts and I get bloated, little campy feelings, and sore boobs a day before my cycle starts.. I've been experiencing all of those plus on and off nausea, fatigue, and minor headaches and dizziness for about 3-4 days now.. Could all of this be in my head? Or could I actually be pregnant?