Just wanted to ask other champ doggers their experiences in whether the size of a pregnant bitch is a good indication thow many puppies she will have?

Not really.  I have had a petite bitch who was quite large to have 9  AND A BITCH THAT LOOKED LARGE WAS VERY FULL OF WATER AND ONLY CARRYING FOUR, AND A DEAD ONE.

When my Staff bitch was expecting, she just looked like she had eaten a bit too much!  I'm sure people thought we just had a slightly fat Staff!  She then went onto produce 6 large, healthy pups!  :-)

I guess it really depends on the musculature of the bitch and how she is actually carrying the pups.