Outside cat

I have indoor cats but I just moved and inherited an outdoor cat. It is technically the neighbor’s cat but I feed it and it hangs out with me in the mornings and evenings for about an hour each. She is very friendly and I know she had kittens a few weeks ago. I’ve never seen the kittens and the neighbor said they haven’t seen the kittens in a little while. I’ve been trying to figure out if she is still nursing but do not know enough about outdoor or nursing cats to tell. If the kittens are still alive, they would be around 3-4 weeks old. Mama cat’s nipple areas are not engorged, the fur around them are still brown (she is a mostly white cat), but her nipples are a very pale pink. Do y’all have any insight or opinions to if she is still nursing? (I did not think this was a vet question, but if it is, I’ll be happy to remove the post)