Re: Pregnant, or bug? And even more...
If she gave birth she obviously was pregnant. Next time you wonder if a Sim is pregnant click a toilet and choose "Take pregnancy test". If the option are not there they can't be pregnant. For the problem with overweight Sims take them to the Gym or buy the equipment for home.
What Vet machine says the dog is fine? Did you take it to the Vet and sign it in for a checkup?
Do you have any Mods or CC? If so move your Mods folder to the Desktop and delete localthumbcache.package. Then test the game.
If it works now check for updates to your Mods and CC. Add it back a little at a time while testing until you have found all that are broken.
