As the title says my period is late. It's 6 days late and I usually super regular, I can't remember the last time it was more than a day late. I am definitely not pregnant.
How long before I need to worry/do something about it?
I have googled and it gives several reasons, stress, well now I'm stressing about this! But I'm not generally stressed.
Low body weight, yeah right 
Increased exercise, I have increased my exercise over the last week but not dramatically only half an hour a day!!
If anyone has any advice I would be grateful 