Sims 3- Can't WooHoo/ Try for baby

My Sim recently got married to her boyfriend. She had triplets (I bought both a fertility treatment) and now there is a total of 8 Sims in my household. My adult girl Sim, adult boy Sim, young adult girl sim(adult boy Sims daughter), young adult boy Sim, and the three triplets who are toddlers and all girls. Both of the parents are adults and three star celebrities.
When I had them cuddle on the bed to get them to WooHoo, the option wouldn't show up, and neither would Try For Baby. I have Latenight expansion pack, and that's all, so I don't know what the problem is. How can I get the option to reappear?