Clear Blue Test

Ok so I went to the doctor last week and they said I had a negative pregnancy test. I was thinking maybe I tested too soon because I know my body and I haven't been feeling right for these last couple of weeks. AF is not due for 3 more days, BUT something told me to test today first thing in the morning like I was supposed to and I got a BFP!! I am so excited but nervous at the same time. How accurate are these? They won't say yes and be wrong will they? Has anyone ever had that happen? Sorry I'm new to this and have heard of it saying no and being wrong but not sure if anyone has experienced it saying yes and being wrong. Please please help!