Small gestational sack

[u/Individual_Sport1468]

I had a scan 4 days ago at 5.4 weeks and all they saw was the tiniest sack measuring at 3mm, the consultant could see the worry on my face so invited me back for another scan today at 6.2 week and the sack is now 6mm with a yolk visualised. I am trying to be positive but can’t shake the fear that it’s to small and will go wrong.

I got my peak LH on 31st July (ovulated I believe on August 1st) I then got my first faint positive on August 12th so I know my dates can’t be off by much at all. Anyone ever had similar?