Pregnant Sim Won't Change Trimester

I used the cheat: sims.add_buff buff_pregnancy_trimester1 to make my sim pregnant. She immediately got pregnant, however whenever I hovered over the "eating for two!" icon, I thought it usually said something like "2nd trimester in 5 hours", but that's not there. I didn't think much of it and moved on but when about 3 sim days passed, her pregnancy didn't change. At this time I tried the cheat sims.add_buff buff_pregnancy_trimester1, 2 and 3 and then sims.add_buff buff_pregnancy_inlabor, but nothing worked. Please help!