The mature dog will look quite full in the body. However, the almost square outline should remain, and the adult dog should be half leg and half body in the front.
In other words, half the height is from the withers to the elbow, and the other half should be from the elbow to the ground.
Dogs who go off proportion, who are longer in body or shorter in leg can get that squat look you are speaking of, paco. I am seeing a return to more correct proportions after some years of seeing way too many dogs out of proportion.
At this age puppies will naturally look a bit more up on leg, since they have not bodied out. They should turn out very nice, both these boys, altho frankly the heads may go a little overdone for me on both of them. Most of the time you will get by with that on males.
A couple more shots so that you can see body proportions on these dogs. I measure them in photos quite often. The dog should be 9 part height to 10 parts body length.
This is not a great shot, but in this photo you can see just how much leg he had to grow into at 8 months. (Mike) And also his pretty decent shoulder/front.
Notice that the brisket is not quite down to the elbow yet in this photo. As he matures, the scapula will lengthen. The upper arm won't change much.
You can see in this photo that while he has very nice top skull, it is not domed. Also clearly observable is his most obvious short coming, needing more turn of stifle.
Here is Milton at about the same age. The structure is there, but clearly it is only a frame on a puppy that has a lot of filling out to do.
This puppy has the better rear of the two, altho the lack of body due to his age makes him look slightly longer, he is also correctly proportioned.