Help!! Could I be pregnant?

I am so frustrated! I am 4 days late and have taken 3 pregnancy test over the weekend and they were all negative! I am never late so I have no idea what is going on. My periods are usually 34-35 days apart. But I have so signs of a period starting. My breasts hurt, I have had some nausea and felt a little pinching in my uterus. Is it possible I could be pregnant? Should I go get a blood test done?