Is my cat pregnant?

Hello. Does anyone know whether this cat is pregnant or not? I know you can't tell for sure just by looking, but I have a feeling she is. A male cat got into my house twice(he was stray) and she hasn't been spayed. Also, there was some blood on her vagina after the second time he came in. I'm assuming this is from him mounting her? This happened about a month ago, so if she is pregnant, I'm not completely sure how far along she is. Both pictures are of her laying down.

Have you noticed is her nipples have gotten more pink? That usually happens around day 21.

It's likely that she was pregnant if not spayed and around intact males.