What Are The Symptoms Of Pregnancy?

i m 16 years old and i had sex for the first time about 2 weeks ago. Just this week i have been feeling a bit paranoid. Yes, my partner and I used contraceptives while we had intercourse. And checked the condom afterward to see if it was broken, (as well as before) however I m experiencing some strange changes in my body such as, darkening around nipples, a line under my belly button going downwards and slight headaches but only on one side of my head. Is it possible that these changes could just be occurring because my body thinks it s pregnant due to it being my first time?? Please answer, this is urgent and i m scared.