Little Nemo, go to the doctors and get checked out. I've got the same issue at the moment and am 42. My doc did loads of blood tests cos apparently can also be caused by liver, kidney or thyroid problems, which I'm sure you haven't got, but best to be sure. I've always been very regular but periods suddenly stopped and apparently it's not uncommon for the menopause to start this way without any other symptoms....I haven't even had any hot sweats, but test results showed my hormones are menopausal. Everyone assumes that we go through it at around 50. Doc says 51 is average in UK, but early 40's is within normal range so nothing to worry about.