Why is everything messed up!?

So recently, meaning the Sims 4 has been stupid for the past two weeks. I haven't downloaded any new mods or CC other than updating MCCC and UI. But the sims will not let me save my game without going into manage worlds. Does this mean when I leave the game, it doesn't keep cause who goes to manage worlds to leave the game? And then the past two days, I deleted my previous save cause my CC was wiped from said keep after the update, and I didn't feel like redressing them (relatable), and the stuff that I THOUGHT saved cause I did; manage worlds at some point, wasn't there! Anyway, I created a new sim; she's perfect. What is not perfect? I put down a gallery lot and then realized, "Oh I don't like her shoes" or "Let's change her career outfit," and after leaving cas, the build is gone! And I thought maybe the apartments were glitching until I tried to place a restaurant down, and it disappeared as soon as I moved to manage worlds. I don't know what's happening, but what I do know is that after repairing the game three times, restarting my computer once, and exiting the game one too many times wanting to cry in frustration, I'm done trying to get it to work on my own and would like help. I don't even know what kind of help would work, but I need help!