Lots of things delay a period besides pregnancy: stress, weight change, hard training, perimenopause, PCOS, thyroid problems, and hormonal contraception all make the NHS list.
Sometimes the cycle just varies on its own. See a GP after 3 missed periods in a row, or sooner if other symptoms tag along. Pymander is a free AI doctor, 24/7 by text, and can help you narrow the list.
What to do
Common questions
Why is my period late but I'm not pregnant?
Pregnancy is the famous cause of a late period, but the NHS list of everyday causes is long: stress, significant weight gain or loss, very heavy exercise, starting perimenopause (usually between 45 and 55), polycystic ovary syndrome (now also called PMOS), and hormonal contraception such as the pill, the injection, or a hormonal IUS. Sometimes there is no cause at all - the gap between periods simply varies, which doctors call irregular periods. MedlinePlus notes most cycles run about 28 days, but anywhere from 21 to 35 days counts as normal, and cycles take a few years to settle after periods begin. Underactive or overactive thyroid, diabetes, and other medical conditions can also pause a cycle. Worth doing first: if there is any chance of pregnancy, take a test even if you think you are sure - it settles the question in minutes. Then the NHS lines: see a GP if you have missed 3 periods in a row, or if the missed period comes with weight change, tiredness, new hair growth on your face, or skin changes. A GP may run blood tests to find the cause. Pymander is a free AI doctor, 24/7 by text, that can help you think through the list.