When would pregnant dogs abdomen start to thicken?

i had my ***** scanned at 25 days and vet said there were no puppies, my question is she is obvisouly having a very severe false pregnancy and her ribcage is even noticably expanding as well as other signs, she is a large breed and a mating was planned and appeared successful. she is now 35 days ,so if she were pregnant would it now be apparent visually?