Sorry an early ultrasound would be done anywhere between 5-7 weeks. Usually around 5 just to confirm there is a sac at the very least. They are not necessary so docs usually forgo them unless you have a history of loss or something of concern going on.
Nurses are ill trained to interpret results, so listen to the doctor over the nurse. Kaiser won't even let the nurses talk to you about the results because they freak people out so much making comments like that. If you were going to mc, you would have gone down or not been doubling. There is always worry in the first tri because things can change, but for now everything is as right as rain.