Rotational play might be the way to go for you. Turn off aging for everyone but the active household. Then play as always, but whenever you get desinterested in a household, add your new sims to the same save. Soon you will have a web of co-workers, friends and rivals. Think of boring job tasks like "Get to know a sim at spice market" or "Talk to another social media career sim" - they are much better if your new sim does them with one of your old ones.
You said you enjoy giving your sims backstories and posting about them. In this case you'd probably also enjoy giving your whole sims world an overarching goal or theme. Some element that will be present in every household. Maybe all sims have the same ethnic heritage, but adhere to it to differing degrees. Or maybe the neighborhood has some very strict building guidelines that can only get lifted if you have a sim at the top of one each of politics, interior decorator and civic designer. Or a new fashion trend emerges and everyone now includes pieces of one or two specific packs. Think of mini challenges that would be painful for your sims (for drama), but fun for you as a player!
That said, as a serial restarter myself, I don't see anything wrong with your way of playing.
