I know you said you tried everything, but I have a recommendation just in case, for you and everyone else:
In my experience with ants, only one product has worked: Raid's Bug Barrier, which you can get here on Amazon or at pretty much any big box store. My building has a horrible ant problem but I almost never get them.
It doesn't work like typical bug spray, it creates a scent that repels them and (I suspect) is similar to whatever your exterminator uses.
When I use it, I will wait until I see a trail of ants. Once I see the trail, I'll follow the trail to find the point of entry (usually a crack in hardwood, or an outlet, or a doorway). I'll spray a small amount on the point of entry, then wipe up the trail with a normal cleaning spray like Method or whatever. Genuinely once I do that, they won't pass thru that spot for at least 6 months.
(For people who aren't OP: if you have a bad ant problem already, there's gonna be an element of whack-a-mole at first: find trail, spray entrance, wipe up ants, repeat - don't give up! Eventually you'll get every entrance, it takes maybe a month).
Anyway, that's my advice on ants. Raid claims Bug Barrier is effective against roaches and other bugs, but in my experience it works on ants and only ants, but it's fucking lights out.