Sims 4 has no story progression so this is impossible without mods, or without playing all the different households to make sure they get kids as well. In sims 3 NPCs would get married, have children and careers etc, without you having to interfere, but this was removed for some reason.
However, in my experience MC command will fix ALL of this. If you want a certain sim to have kids, you can click them and mark them for "marriage", which will make them marry a randomized sim in the next marriage cycle, and after that they will usually get kids as well. It works pretty much like the story progression in the sims 3.
I have avoided modding for years (thinking it would be hard to do and buggy) but I eventually realised that MC command was essential to my gameplay, and i was pleasantly surprised to learn that it was really easy to install mods for the sims.