Confused!

Carleigh • Mama to a sweet little boy with another little one on the way! ♥️

So I’m trying to determine how far along I am. The first day of my last period was February 21st which would put me at just four weeks today and Baby Center says that we conceived on March 7th. This doesn’t seem right because I took a pregnancy test March 14th because I felt “off.” Positives don’t usually show up until 2 weeks after ovulation right? Can anyone help me out? I have an appointment with my doctor on April 4th, but I’m just trying to figure it out!