What’s going on??

So, I am 9 days late on my period. Normally my period is on time if not a day or 2 early or late. Never usually this late. We have not been very careful. I have had minor cramps but no bleeding, no other signs of pregnancy or a period. I have taken a few tests that have come back negative… what should I do? Should I wait a little bit and test again?? We did have sex on my ovulation day.