Inga, I've never had the numbers you seem to have had, but it seems like I had a bit of an explosion at first, and now there are just a few on the glass. I have been fishing the ones on the glass out, but there are still others that I've left alone. Maybe I've just become used to them, or maybe the numbers have sorted themselves somehow.
I just did a water change and used that vacuum thingy as well and, looking at the gravel closely, I can see the little snails down in the gravel in my 165-litre. I really don't think you'll ever be able to get them all out without resorting to stripping down your tank and maybe using chemicals to nuke them. Then, the minute you get a new plant, they'll be back. That's how I think I got them, and I rinsed the plants and looked them over before planting.
Maybe your numbers might settle on their own if you let things be for a bit to see what happens? I think that getting rid of them all is a losing battle. The snails will win, so you may as well get your white flag out
ETA: I never removed my plants or driftwood as you have.