For the mods error message, what kind of install is this? ErrorTrap has different versions for 1.67/disc, 1.67/Steam, and 1.69/Origin installs; getting the wrong one can throw the mismatch error. If you're not sure which one you have, just trash it and download the correct one. Also, if you have Showtime, install NRaas Traffic. The career performance limos can spawn by the thousands every day, which will slow down the game long before Overwatch has a chance to clean them up at night.
Most of the tips in the Steam thread you linked are either fine or neutral, but step 4 can cause problems. Sims 3 is already large address aware and has been since 2010. The value in the screenshot is for the script heap limit, and it's 20 GB, not 2. If you've made this change, please undo it.
Whether step 4.5 is a good idea depends on your exact CPU. The rating determines the load on the processor in some ways, and yours might not be able to keep up. I can't tell by the specs you listed which one you have, but, for example, an i5-7300HQ can probably handle being rated as uber, whereas an i5-7200U probably can't. So it's probably better to undo this change, see if you can get the game to run well, then maybe bump the rating up one notch and see how it goes.
Of course, the bigger issue is the GPU, and yours probably can't handle the most demanding packs (Pets, then Seasons, then Island Paradise and Into the Future) very well. Some people with similar cards can run one or two of those, some can run everything except Pets, some can't run any. So you'll need to experiment with this as well.
Since you used the Steam guide, I take it you've confirmed that your in-game fps is locked at 60. But if not, that will help performance by a significant amount.
Not having any idea what custom content you've installed, I can't say whether that's having an effect. But you might want to test with no cc at all, and only NRaas mods, to make sure the lag is unrelated. Even one bad cc item can cause lag under the right circumstances.
The other point is that some worlds, both EA- and custom-made, cause lag on any machine. (Isla Paradiso is the worst offender.) Test in Sunset Valley, Riverview, or Twinbrook (first without cc, then with) to establish a baseline for performance, and figure out how many packs you can run and whether you can force-rate your CPU higher than the game wants. Then you'll have a better idea of what your laptop can handle. If you really miss a pack that your system can't seem to handle, it might help to instead play in smaller worlds; there are a number of custom ones that are well-made and beautiful. You can ask in the general discussion section for recommendations.
If you still get lag after uninstalling all four demanding packs, removing all cc, and playing in one of the gentle EA-made worlds, you might have a system issue. You can run a dxdiag, post it at pastebin.com or some other free filesharing site, and link it here.
https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/
Once you have a general idea of how your game runs, it's easy to adjust or respond to changes. There are so many reasons Sims 3 can lag, stutter, crash, or otherwise not run properly, it can take some time to sort things out. But as long as your laptop isn't overheating, and your fps isn't running out of control, the game shouldn't cause any damage to your system.
