Hey, with DS it was quite obvious in the ultrasound you could see the bits. With DD I got told at most of my ultrasounds that they were 70% it's a girl and she was. a couple even explained about seeing 3 lines and all the rest.
As for sizing... Both my kids went straight into 000 DS 8lb5 DD 8lb10. DD was only in 000 for about a months as she was quite long. Personally I wouldn't buy too many 0000 incase bubs is too big and if they're not too big you can always go get a couple more once bubs is born.

Goodluck with your ultrasound and I hope you get to see what your having.


Ellie