hi. i am on birth control but after not even a week of taking it i had unprotected sex. three weeks later i was supposed to be on my period, i was three days late, it was light and only lasted about two and a half days. eventhough i thought maybe i was over thinking it, i bought a pregnancy test. the test result had a dark line appear as soon as i peed on it, and after the amount of time i was supposed to wait another faint line appeared making it look like a plus. it was very faint and i was still unsure so i planned on taking another test this week. i woke up yesterday with what was like my period but its not do for another three weeks, a little later it was still like my period but brown, that lasted all day and today its back to blood. is something wrong?