Period is late but don't feel pregnant

Has anyone not felt pregnant but turned out to be pregnant? We're coming to the end of the month and I'm currently over 9 days late from when I typically he my period even if I'm a few days late but don't feel pregnant was going to test on the first but I don't feel pregnant nor have any period symptoms, I have cramps like I did with my first pregnancy but not period cramps, I'm not sleeping more then usual yet or anything. What else could be wrong if it comes back positive? I've never missed a period in my life beside the first time I was pregnant and last month period only lasted 3 days where as I'm always 7 days. Should I seek a doctor if it comes back negative?