I just got an 11 month old female rottweiler and she is very skinny. The last owner said they wormed her. I didn't see any worms in her poo and I noticed it's a little soft, not runny though. She doesn't act like she's starving at all. What should I do?::(

If you just got her she might be getting used to drinking the water at your place making her stools a little soft. Just like when you go on vacation and they say "don't drink the water" or you will get diarrhea. A dog who is otherwise healthy and active but skinny is perfectly fine. More health problems from being overweight and inactive. The vet will examine the feces under a microscope and look for worm eggs or tapeworm segments or even evidence of blood in the stool called occult blood since it will be brown and digested instead of fresh and red. You can't judge this with the naked eye. Worming is done periodically as a therapeutic to keep your dog healthy. Some worms can even be spread to owners like if you walk barefoot in the grass and accidentally step on a patty... so better safe than sorry.

Take her to the vet for a check-up first thing. She is young and will fill-in, I'm sure you'll notice if she is eating or not.

Are you feeding her a dog food that is nutritionally balanced? Some of the store brands, and most of the no name/cheaper brands have a lot of filler, and little nutrients. You should definitely have her checked by your vet to rule out any health problems.