Hi . Welcome to HCM forum. Hydrochlorothiazide is a diuretic drug that flushes out urine from the kidneys. A home pregnancy test detects beta-HCG in urine. If the urinary levels of beta-HCG are too low, it may sometimes cause a negative result, and more so because u are on a diuretic medicine that may dilute the urine concentration. Its best to test for pregnancy with an early morning sample of urine. Another option is to test for beta-HCG levels in serum. That can be done in any clinical laboratory by taking your blood sample. It is more accurate because the levels in blood are higher than that in urine. On the other hand, you might not be pregnant. And the delay in your cycle may be due to some other medical reason, or may be a normal process of attaining menopause (as you said you are 42yrs old). Get a thyroid profile test done. A disturbance in levels of thyroid hormones can also cause these symptoms. And its very common these days. I hope I answered your query.