I need your thoughts please

I am a week and a day late on my period. My period is normally on time or a day late at most. I have taken 3 tests all which came back negative. I am showing no signs on the AF but i am not understanding the negative tests results. Is AF just really late this month? (on a side note my husband and i have been ttc for 5 years...so for my period to be this late..has us hopeful but its shot down after every test coming up negative. We are sooo confused!)