AF Late

Melissa
AF is late. Was supposed to come yesterday but nothing. I FEEL like I'm going to start because I'm feeling pinching and cramping down there. My lower back has been pretty sore for a few days. I've been horribly nauseas for 3 days now and my breasts are so tender it hurts anytime I move.. I've only been a couple days late ONCE in the last year and a half so I'm a little confused. Was wanting to wait to test, but I'm going crazy! Is it possible to feel like you're going to start, but actually be pregnant? 
Help. Advise appreciated.