Okay, that sounds like the things I would do. I think the answer is OCD and if you have PTSD ( then maybe both).
I would find another therapist if this one doesn't think you have OCD... That's pretty textbook. I get obsessed with the strangest things also. I have to unplug everything. I'm never quite sure the door is locked (even though I checked it 25 times) : ) I have to tap the burners on the stove 3 times before I go to bed. ..... I do think though that some people are more aware and thoughtful of other people as in your case of the leaves. I see nothing wrong with that. One leaf wouldn't probably hurt though : )