18 day menstrual cycle

[DonnaPH04]

Hi. I’m 39 yrs old and my usual cycle is 26-27 days but this month my period started on day 18. This has never happened before and I’m so worried something terrible is wrong. Has anyone else experienced this and everything turned out normal/fine? I can’t contact GP to discuss as it’s the weekend.

It's more likely to be perimenopause as periods often become more erratic, I'm 52 and well into mine and one of first symptoms was longer or shorter cycles.
I personally wouldn't worry if you don't have any other symptoms which suggests anything else more serious