Late period negative test!

Hello, I’ve been TTC for 5 years. Periods all regular, been under the gyno for 3 years. Had all tests (tube dye, scans, colposcopy,) tried clomid, cycogest: husband sperm fighting fit, just been put down as ‘unexplained infertility’

I have kind of come to terms with it and have stopped obsessing…. Until now… my period is 3 days late (never happens, usually comes early and saves me the wait of turmoil. I’ve done a test and it’s negative. Then read the reviews for this particular test and they arnt good but I don’t mind about that: I just want to know if it’s common for people to find out a good few days after their period was due after a negative test that they were infact pregnant? I just don’t see any hope but my period being late has thrown me so much 😩

Thank you!! And help! Xx