When did you see anything on the ultrasound?

Hello everyone, I’m around 5w2d weeks. Wednesday (4w5d) I had my first blood draw at the ER and it was 639. They did an ultrasound sound but said the uterus was empty. Friday (5w) I got my blood drawn and my hcg levels was around 1542. My ob also said she didn’t see anything but my uterus was thickening. So obviously my level are doubling, my question when did you guys first seen something in the ultrasound sound and what was your hcg at the time. Crossing my fingers that this pregnancy is going good.