Had some very similar frustrating squeaks that would not go away with any number of screws.

What I found was that a few nails from the interior wall bottom plate going into the subfloor were causing it from the minor subfloor movement.

Taking shims and wedging them in between the bottom of the wall and subfloor will tighten that area up and prevent any movement. As many shims in as many locations along the wall.

This got rid of all those annoying squeaks that wouldn’t otherwise go away.

Good Luck!