If she is having quite a few pups then its normal for her to start showing at this time. They normally start to show around 5/6weeks but in a small breed like a pug it may be earlier.
Like you say if she has already started to show early maybe shes quite full of pups and needs to go to the toilet a bit more often. Most dogs house training lapses a little when theyre pregnant, maybe give her more access to the garden, or crate her to see if she can help it or if she just can't hold it in!