Why are my periods irregular despite normal tests?

Normal results do not always mean nothing is wrong — they often mean the right test was not done, or was done at the wrong point in the cycle. Several things worth checking. Hormone tests are cycle-dependent: FSH and LH are meaningful on days 2–3, while progesterone confirming ovulation must be taken about seven days before your next period is due, not mid-cycle. A prolactin taken after a stressful blood draw can be falsely high, and a mildly abnormal thyroid result can be dismissed as normal when it is contributing. Then there are causes that do not show on standard tests at all. Functional hypothalamic amenorrhoea — where stress, low body weight, or heavy exercise suppresses the signals driving your cycle — produces normal-looking scans and often unremarkable bloods. Practical step: keep a cycle diary for three months recording start dates, flow and any symptoms. That pattern is often more informative than another round of tests, and it gives your gynaecologist something concrete to work from.