Within Two Weeks Of Having Unprotected Sex And My Partner

within two weeks of having unprotected sex and my partner came in me. I took 2 pregnancy test which both came out negative. Unsure if I took it to early. possible conception is on 8/8/18. on 8/22/18 I had a menstrual cycle that was heavy for 2 days straight then on and off for 4 days. after the cycle ended I began to feel light headed, dizzy spell, pressure and pain on my middle back now that 9/8/18 mark 1 month, I am feeling discomfort and slight pain in my stomach as if the skin and muscle is stretching. Are those signs of pregnancy?