What Causes Pregnancy Like Symptoms When Pregnancy Test Shows Negative Results?

Yes I am wounding if i am pregnant I haven't have any bleeding since 11/30/2014 and that was just light and lasted 2 days my last normal period was 11/06/2014 I have had most of the pregnancy symptoms like sore heavier brest and gets bigger every day sick all day most days back hurts pains and funny filling in lower abdomen I have put on 5 pound in 2 weeks but every time I take a test it comes up negative