How long after a missed period should I wait before I take a test?

Hi there everyone! I am a bit worried! I am 8 days late on my period. I was due on the 29th of December and usually come on in the morning. I do suffer from polycistic ovaries but my periods have always been regular and if not it's only been a day or two out but the last 3 months have been very regular and every 28 days! Me and my partner are trying for a baby but even though i'm this late I took 2 pregnancy tests one 4 days ago and the other 3 days ago and they were both negative. I really don't know what's going on, could I be pregnant and what should I do, help really appriciated! Thank you.

[Dr. Kokil Mathur]

Hi!
Well, pregnancy tests are positive as early as the day of missed periods in a regular cycle. So you have tested at the right time.  If urine pregnancy test is negative then go for a blood pregnancy test. A blood HCG estimation test would be most reliable. If the test is negative then you are not pregnant. If it is borderline, repeat after a week to see if the levels are rising. Rising levels indicate pregnancy. If this too is negative then other causes of delayed or missed periods will have to be looked at such as ectopics (can give negative urine/HCG tests), stress whether emotional or physical, hypothyroidism, polycystic disease of the ovary, pituitary tumors secreting prolactin, anemia and poor diet, hormonal imbalance, unexplained or sudden weight gain or weight loss. You will need to consult a gynecologist for this. Take care!