False Positive

Salam mommies& mommy-to-be My period is 5days late ahad minggu lepas, so i took a test and seems like double line. Then today, took another test, its negative. Pastu terus pi clinic to confirm it.. Dekat clinic pun, UPT is negative. Doctor scan, tak nampak pa pe pun. But dinding uterus mcm dah tebal doctor said.. Doctor suggest we wait for another 2more weeks.. then we will go from there.. Anyone pernah alami situasi yg sama?