21 weeks & 4 days NO APPETITE!!!

In the beginning I had really bad nausea so my doctor prescribed a pill to help it go away so that I could eat & keep food down. now I'm out of pills I'm able to keep food down much better without the pills. But now I have absolutely no appetite is this normal? I don't eat like pregnant person I'm only worried about my baby possibly not getting the nutrition she needs. Sometimes I will be super hungry but the minute my plate is in front of me & I take a bite I am like completely full.! Is this normal???? Please help!!