You're doing all the right stuff.

It will be easier when the leaves are off.

Often people think of city squirrels when they hear about squirrel hunters. A wild squirrel in the big woods is a total different animal. Especially if you're in an area with lots of predators.

They hide well. They can freeze on a branch for a long time waiting for you to leave.

Keep hunting the food sources. You'll find them.

Some areas have less than others of course. Keep at it.