Hyee

I have always my regular periods mean if it starts on 2nd january it will come exact on 2nd in february.

In the month of July my menses date was 5th july. during this i had unprotected sex witha desire to be pregnent whole month.
after mid of july i fell my breast were swellen and frequent urination. i thought i am pregnent, i test through pregnancy strip on 3rd august but it shows negative result. I was expecting me periods on 5th august but it cam on 8th august ( i never had 3 day late periods whole life and normally i got huge amount of pain during periods but not this time.).
The periods dicharge was darkbrown and it was not heavy one .and there was no pain or cramps during bleeding and in 8th night there was not bleeding its only on day timing

i want to ask can i be pregnent?
is the dark brown bleeding is normal?