@MarMarcin If you move hometowns using the in-game function (i.e. the phone), it makes sense that much of the data from that save will be preserved. The best way to start over is to save your sim family to the in-game bin, save the house itself separately if you want to keep it, and place both in a new save. Make sure to quit to desktop before starting the new save; if you switch at the Main Menu, some data from the old save will transfer into the new one. After you quit and before you start the new save, delete the cache files in your game folder as well.
Another option is to use Save Cleaner to reduce the size of your save files. It's easier to use than S3PE, and will probably do a more thorough job. Here's a discussion of Save Cleaner that you might find helpful, starting with this comment:
https://forums.thesims.com/en_US/discussion/comment/15419659/#Comment_15419659
The links in the first comment are broken, since NRaas has moved to a new site, so here are the old links via the Wayback Machine:
https://web.archive.org/web/20180228113005/%20http://nraas.wikispaces.com/Deleting+SNAP+resources+FAQ
https://web.archive.org/web/20180207093234/%20http://nraas.wikispaces.com/Kuree's+Save+Cleaner
The EA version of Isla Paradiso is so poorly made that it's almost unplayable, even for the most powerful computers with the most effective mods. If you want to use it, you can either download ciane's fixed version, or copy the edits she made into your own game. Otherwise, your save will lag and glitch and generally be impossible to play forward after a very short amount of time. You can read ciane's documentation of her work and/or download her fixed version of IP here:
https://forums.thesims.com/en_US/discussion/811253/removing-ip-lag
The mod you need to assign opportunities is NRaas MasterController. It's quite useful for the commands it makes available, but it will never do anything on its own—the player has to directly force an action. So there's no reason to remove it; you can just ignore it until you need it again. To assign the omni plant opportunity, click on your sim and then select NRaas > MasterController > Basic > Opportunity: By Category > Gardening > The Omnificent Plant. Make sure that you've cancelled any skill opportunities before you do this, or no new ones will show up.
If you later decide to add mods that specifically prevent glitches and remove corruption from your game, you'll want NRaas ErrorTrap and Overwatch. Register and Traffic are helpful as well—they control the game's Service and Role sims, and the spawning of vehicles, respectively.