Talk to Gynecologist on Periods Problem

hello...my usual cycle is of 28-29 days..last time it was 4 days late... this time I expected them after 28 or 29 days on 23dec but periods didn't appear...then I waited for some more days after 4 days on 27dec in evening I have 2 cloudy mucus clots in evening..I thought it is start of my periods (coz generally my periods start with tiny clots for 1-2 days)but nothing happen in next two days(which is unusual)..is there any possibility that I might have conceived or there could be any other reason( I never have a missed period ever)