Advice?

Hey guys! My husband and I have been TTC for 7 months with no luck. As of today, I am 1 day late with my period. I took a digital pregnancy test first thing this morning, and it was negative! Any thoughts on this? Has this happened to anyone else and you really were pregnant? I have an appointment for an unrelated visit with my obgyn this coming Friday anyways (6 days away). Anyways, I'm just curious if this has happened to anyone else and you really were pregnant! Please let me know. Thanks in advance :)