My period is 3 days late iv been tryin for a baby for 4months, period is every 28days, done 2test both back negative but have bad cramping in overies?

Anovulation: The most common cause of a late cycle without pregnancy is anovulation, not ovulating. You may start your cycle in a few days. If this happens a lot, it may cause you difficulty in conceiving. I would recommend following up with your physician. Also, you may want to have a blood pregnancy test to be sure that the urine tests were correct.