Pregnancy symptoms or am I overthinking?

So I had sex (with a condom obviously) for the first time over the Halloween weekend. We checked for any breaks in the condom after by filling it with water and there was nothing, but he did cum inside me into the condom. I'm supposed to get my period in 2 days but I've noticed I've been a bit nauseous, my breasts are abnormally firm, and I'm really not having any usual symptoms of PMS that I get. Am I overrreacting? I'm 17 and even though the person I had sex with is my boyfriend of 3 years I'm still nervous, because we waited until we both felt ready so it would be really awful if something like that happened.