nipples really sore!!!

Hey ladies well I am 4 DPO and 9 days away from my AF and literally my fiancé and I have been TTC for about 5 months now. Without us even thinking one night on checking the app for the percentage chance of us getting pregnant, we had sex on the highest point of my ovulation. And within like four days later my nipples started to feel really sore and my breasts seem to be really heavy. Is this the early sign of pregnancy or am I going crazy???