I don’t think she is at the moment because when the topic was brought up by Kelly on season 12 finale she didn’t seem to happy about the idea as it’s going to have a great affect on her being a lieutenant and if she has a place at 51 because if you remember back when Dawson was pregnant, she wasn’t allowed to stay at 51 she had to take a desk job
Too much too soon Stella did not look happy when Kelly mentioned starting a family. She did not say anything. Could be she might not want to be Pregnant.