Sorry to hear that you have been having such difficulty. In this hobby it is never easy to find permissions, and public places are often hunted to death. What I usually do is try to find places other people likely never thought to check such as tiny public grassy areas such as the 6ft x 20ft front lawn of the police station maybe, places that are difficult to get to (which restricts the crowd by a LOT), or government land that is not marked as such like old buildings leased by a government office. Another thing to try is research old maps to maybe locate ghost towns, mining or logging camps, etc. where there is a history of being occupied but are now abandoned.
Everyone goes through dry spells. I was on one for some time before I suddenly found my first largie, and then my second soon after. Just the way it works sometimes, so just don't get discouraged-just keep digging