What Causes Delay In Periods And Tender Nipples?

hi, my last period only lasted 2 days when it is usually 4 i did a test 2 weeks after and it came back negative, this months period however is now 5 days late. For the past few days i have felt as though i am going to have a period but today them symptoms have gone, i have also had tender nipples the past 2weeks. Could i be pregnant?