Soo confused!!!

So I have took 4 pregnancy test all which have been negative. AF was suppose to visit on the 19th and she still has not made her apperance! We are ttc so another baby would be amazing.... But y are all my pts coming back negative???? Should I go to the doc to get blood work done. I also have the same symptoms of pregnancy like my girls are sore!!! And I'm nausea most of the time also very tired but these also come along with AF every month for me so.... I have no idea!!!!! Very confused!