
No, a Pug is a Pug is a Pug!!
The breed standard is 14lb-18lb, so you would expect a bitch of 6mths to weigh at least 10lb. If she is registered she
should be a purebred, but stranger things have happened!
Just out of interest have you taken her to the Vet to have her checked over? (don't expect the vet to say whether or not she's purebred tho!).
Go
here for Pug Club contacts if you want more info.
Good Luck with her anyway, she sounds a lucky little girl