7w4d gest sac measuring small

I went in for ultrasound and they said they couldn’t detect heart beat because the gest sac was still too small. They seen an embryo that measured correctly (had ultrasound 2 weeks ago and it is measuring about 5w4d at this ultrasound I measured 7w2d. Doc says that the growth looks good but they couldn’t detect a heart beat yet bcuz of the gest sac. Anyone else have this?