Girls good day! It's been 20 days since my period started being late.…

Girls good day! It's been 20 days since my period started being late. Last week I had an ultrasound, and they said there is no pregnancy, follicles are maturing on both ovaries with a diameter of 10mm. But I feel like I have morning sickness, I feel nauseous all the time, and I smell fish like in my previous pregnancy. I hate that smell. Nobody else feels it except me. Could it be pregnancy? Shouldn't it have been visible on the ultrasound?