what is going on?

I was rading another thread a/b a girl who was worried b/c her period is late. I feel the pain. I usually go 4 1/2 to 5 1/2 weeks, although I have been known to go six I haven't done it in over a year. Looking back I noticed that a couple years ago I went six weeks at one point and over seven weeks two other times. I've been extremely stressed this month. I mean to the point that I start shaking and I make myself sick to my stomache. It has now been six weeks and I'm confused. I experienced all the normal signs of having my period--larger than normal tender breasts, bloating, moodiness, increased appetite, I even had some cramping fri and Sat, and my breasts are still larger than normal, but I haven't started. I get very anxious very easily, and although I feel like something is going on inside me--I'm getting the normal feelings i get every month--I still don't understand. why would I go through all of the symptoms and then not start? Help