Is this crown to rump length a normal size for 6 weeks?

[Mruffolo]

My ultrasound yesterday showed I am 6 weeks 0 days as opposed to 6 weeks 4 days like I thought. My crown To rump length measured 0.37cm (3.7mm)

Does that sound right? Or is that measuring too small?

 

[Oliviasmommy]

I went at 6 weeks 1 day and didn’t have a fetal pole at all. I go back this Tuesday at 7 weeks 2 days to see if there will be one. With that being said, I wouldn’t be concerned.