TTC for months

Hi ladies, We have been trying for our first baby since February of this year, and nothing , my last period was June 5th. It’s been around 125 days since I’ve last had a period, but still tests come back negative. I’ve never had this happen before , I’ve always been regular never missed periods before, never even been late. The most late I’ve been was like twice and only 1 day late. I have a doctors appointment soon but I can’t get the thought out of my head , what if somethings wrong. Has this happened to anyone before, and turned out you were pregnant, or any similar experience?