Could I be pregnant? The first date of my last period was on 5th July, it lasted til 10th July. My cycle is usually 31 days. I had unprotected sex on 27th, 28th, 29th and 30th (trying for a baby).. From around the 2nd August onwards I ve been experiencing extreme fatigue, light headed and dizziness and extreme sense of smell. Today I ve bled a little (possible implantation bleeding?), a light pink and also a dark brown bleed. (Sorry if TMI). My test is still coming up as a negative, GP said it is still too early for a positive result. What is your views on this, and how can you tell the difference between your usual period and implantation bleeding?