Measuring 5 days behind

I had an early ultrasound today due to my history. From my lmp I would be 6w today, unfortunately there was only the gestational sack seen. The tech said that I look to be around 5w2d and that it may just be to early.

She was happy with that and said it is within time frames for dating give or take.

Has anyone had this kind of difference and it all turn out OK?

This is my 4th pregnancy however the first time I've been able to have the chance to see something where it should be (1st 2 I miscarried before 6 weeks, the last was pregnancy of unknown location) so there is hope in that.

Just looking for similar experiences to help calm my anxiety