My last period started Jan 2 and the last day of it was Jan 7. the only time before that I had sex was Dec 3. The last time I had sex was this past Wednesday Jan 11 and we used the pull out method (and yes I know that is not a good idea). Today Tues the 17th I started have a very dark red almost brown discharge and its been going on for most of the day. Could that be a sign of pregnancy already? Please help.