Period is late but negative tests

We are ttc and I have tracked my cycle on two different apps for the past few years and both of my apps said I ovulated Feb 14. We had unprotected sex the Feb 12-14 and my period was due Feb 28. It is now March 7 and my period has not come yet. I tested this morning and it was negative. I do not have any symptoms besides nausea and I don’t have any cramp pains that usually come when my period is on the way. I’m thinking I ovulated later than the apps said.....