I've got a Squier Jazz Bass Standard, and it rattles a lot, probably cause I have the action pretty low (but I like it low, and I want to keep it low). I took it to a local luthier to see if I needed some fret leveling to fix the buzz but he said that it wasn't necessary, that I only needed heavier gauge strings, or just a setup. I'm a real noob at this kind of stuff, so I really don't know, but I was investigating on fret leveling and I heard that Squiers don't get good leveling jobs from the factory.
It still buzzes (sometimes) when I play lightly (I usually don't play with a light touch

).
What will get rid of the rattle? I really hate it. Is it the setup? (I haven't took my bass to get setup in a while) The string gauge? (I currently use 45-105) Or the fret job? (I hope it's not, I'm looking to spend less money possible) Or... something else?
If it's the string gauge, I know that it will change the feel and tension (and I'll have to setup).
Sorry if I sounded kinda ignorant but I really don't know about this subject and I didn't sleep at all last night...
I need words of wisdom!
Thanks!