I ovulated positive on 11th jan &still no period.had sex 11-13 jan.negative pregnancy test 2days ago.i have pcos, can this be the reason for no period?

Maybe: Pcos can affect fertility in many ways, but the luteal phase is still almost always 12-14 days. It is very common for pcos to affect the accuracy of ovulation predictor kits because your lh is higher than normal, so the test strip can turn positive early, and it is likely to stay positive for several days. This could throw off your expectations. Also, you could have ovulated a second time.

See below:: I am adding to the information provided by dr. Adberg and agree with his note. The only suggestion I have is to repeat the pregnancy test in 3-4 days, use first morning urine and follow the instruction in the kit carefully. Wish you the best.