Decidual Bleeding

Here is a breakdown of why I think I'm pregnant.

Week 1 – Start of Period *Aug. 16* Luteal Phase 28 days
Week 2 – Intercourse *Aug. 27* Conception *Aug. 28*
Week 3 - Decidual Bleeding *Sept. 8 – 12*
Week 4 – No Period *Sept. 13*
Week 5 – Various pregnancy symptoms but negative test result *Sept. 23*

What I would like to know more about is the Decidual Bleeding. It came 4 days before my period was due and lasted 4 days. It started out dark blood spotting then turned into dark blood flow then went to pink/light red spotting and stopped. My period has always been regular and came on time (28 days) never early and the flow always starts out as pink/light red and ends with dark blood after 7 days. So the bleeding I had on the 8th was nothing like my normal period. I took a test but got a negative but I've been experiencing pregnant symptoms like metallic taste, breast tenderness, fatigue, I hate the smell of everything, loss of appetite, sleeping a lot during the day. Am I pregnant?