This happened to me. I went to see the Doctor when I was 14 days overdue and she was very reassuring. She made me do a pregnancy test at the clinic, but that was negative (as I knew it would be!). She said that I was too young for the menopause but that it was not uncommon for this to happen. However, I was to return if nothing had happened by the date of what should have been my next period. What do you know - my next period came right on time but was extrememly heavy. I queried this and she said that that might happen. She told me to go back and see her if I had any more concerns about this, but since then (3 months ago) things have been back to normal. It's good to talk to a doctor about such things, but don't go searching symptoms on the internet as I did and scare yourself into thinking that something terrible is happening.