can’t find the baby on ultra sound

Pls pls help me to understand what is going on with me.. I have an ultrasound today and the technician said there is no baby showing inside me.. Per my pregnancy calendar, I am showing 4 weeks and 5 days pregnant.. My last period was on March 29, and it lasted for 5 days.. My ovulation was on April 13-14 and was supposed to have my period on April 26... Today ( 29th ) I had my ultrasound and no baby showing.. All of my home pregnancy test since the 25th through 28th ( 6 tests ) are all positive.. pls help me understand that this is still too early to see the baby on ultrasound.