No symptoms

I’m pregnant with #4. Currently 5weeks 5 days according to an ultrasound I had the other day there was a sac but everything was so small they couldn’t see much else. I usually have quite a bit of nausea, should I worry if I haven’t had any symptoms besides fatigue and mood swings? I’ve never had an ultrasound so early, they thought I was 6 weeks but since we dont know when I ovulated it wasn’t a for sure. My doctor said everything looked good to him.