My period is 3 days late. I am always very regular at 28 days. sS I took two pregnancy tests this afternoon, both came back negative. I urinated into a glass to perform the pregnancy test and noticed some white clumps floating in my urine, sort of the size and shape of oatmeal. I had a full STI check before we started trying to concieve so I know it is not that. The past 2 weeks I've had alot of pre-menstrual s&s such as cramps, and a very dull lower back pain. Do you think the pregnancy tests could be wrong, or is my period just late?