Period Bloop

Hi I have I have been sexually active 4 weeks ago - two weeks after that I had got light period for 4 days which never got any heavier then suddenly stopped. Sorry for the TMI - it's was brown at the start then reddish then stopped with brown spotting close enough to be black. 
Then yesterday I had bright red spotting only enough to notice when I wiped.. 
Not sure If this is normal because I have never had a period like this before. 
Is there a chance that maybe I could be pregnant? I took a test yesterday but it came out NGTV... Just hoping that maybe it could have been to early.