What Are The Early Signs And Symptoms Of Pregnancy?

I am late by six weeks for my mentrual cycle. I have taken 5 pregency test and all were negative. I havent had any stress or big issues to happen in my life to cause a missed period. The only pregency symtoms I have had is two days of light cramping and a week later light back pain. Do you think its still possible that I am pregnant? Or do you think its another health issue?