Pregnant vs Nursing?

We took in a stray yesterday and we noticed she's either pregnant or nursing. I don't know how to tell the difference and all the vets are closed today. She isn't trying to get out so I'm thinking she hasn't had them yet. Are they any ways to tell the difference?

Her nipples are definitely swollen but not very much. She's really skinny though. We thought about letting her out to see where she goes but we are worried we'll lose track of her. I'm taking her to a vet tomorrow but I wanted to know if there were any tell tale signs.

If she had kittens waiting for her she would probably be trying to get out and go to them. There are so many possibilities, I don't think you can know for sure. She might have just weaned her kittens, or she might be pregnant (or both!), or she might have had kittens that died recently.

Personally I would keep her in until you can get her seen by the vet. If you let her out you might not get her back, and you don't know whether there are any kittens.

Thanks. That's what I decided on doing. I'm feeding her kitten food for now just in case. I heard it's better for pregnant cats.

We are feeding her slowly though because we don't want her to over gorge since she's so skinny. She's the friendliest cat though. Eats a few bites then runs over to get petted, then eats some more, etc.