What's Going On

So I had my period October 20th I was ovulating the October 27th through November 2. Then it says I'll get my period on November 14th. It's now the 17th I'm late and I'm usually never late also I have terrible heart burn, very nauseous and tired. My husband and I are trying for a baby but the pregnancy test says negative I still haven't got my period. What is going on and what should I do?