The weekend finished on Sunday with an afternoon rendezvous at a local golf club with friends & family for drinks, food, laughter and...barefoot lawn bowls. Hilariously fun is really the only way to describe the day. We had a blast and thanks to everyone for making it so special & the effort for travelling up to see Darren.
Now an update from Dr Wikipedia on this most recent medical update;
On ultrasound, it is an anechoic (dark) space surrounded by a hyperchoic (white) rim.
It is spherical in shape, and usually located in the upper uterine fundus.
The mean gestational sac diameter (MGD) is an effective estimate of gestational age between 5 and 6 weeks, with an accuracy of about +/- 5 days. 
The yolk sac and embryo should be readily identified when the gestational sac reaches a certain size and the yolk sac is 20 mm in size or the fetal pole is 25 mm in size.