When did vomiting ahould stop? Help

Krystin • Im 19 happily married with our first baby boy due in april!
I'm 9 weeks 3 days and I've been taking zofran on and off and this morning I haven't puked at all I'm scared something when wrong? I had a ultrasound wensday everything was fine but now I'm scared I've never wanted morning sickness to come so bad! Please help