Could I be pregnant? Please help!

My last normal menstral cycle was Jan.25th. I had unprotected sex on feb 5th. I expierenced mild cramps , weird feelings in my stomach , sharp leg pains , shortness of breath and heart burn feb. 17th-19th. No blood! On the 20th my cramps worsened but no need for medicine. The 21st after getting out the shower I noticed a spot of blood. I put on a pad expecting my normal flow. At the end of the day it was brown and barely anything on the pad. The next 2 days I expierenced light pink - dark red bleeding very light period and spotting. I on the 3rd day I only expirenced light pink-brown spotting. The bleeding stopped but now I have the same symptoms with sore breasts and aching back. My doc said I had a stuffy nose but I don't feel it. My urine came back neg for pregnancy and uti. I never expirenced any of these symptoms before I feel different overall. My period never have been light and I never had these symptoms. Could it be too early to detect my pregnancy?