Am I or am I not pregnant

So 4 days ago I went to the Dr because for about 2 weeks I was getting a brown discharge off and on  that the Dr said was blood I just had a period Nov 30 And lasted til Dec 4th. The Dr performed test and says everything s normal but congrats  ur pregnant. So today which was 4 days after I decided to take a in home test an it says I'm not what do I believe?