Nothing shows on the US

So I went to the ER today because of some pain and I wanted to be sure everything is ok. They did bloodwork and my beta HCG level are at 344 and put me at 4w6d. According to the doctor and the articles I read it's totally normal. He also did an ultrasound but we didn't see much. He said it's because it's too early. Have some of you have had an Ultra sound and showed nothing but everything was fine?