Yep, I was diagnosed with OCD about 10 years ago.
My biggest issue with OCD is that I can't trust my own brain. I'll know full well that I just did something (like shutting a door, closing a container, adjusting something slightly) but can't convince myself not to keep checking it repeatedly anyway.
I first suspected I had it when I was around 13 because I couldn't sleep until I triple checked that the bathroom door was closed and that all my dresser drawers were exactly lined up. Things didn't always have to be clean, but they had to be in "their place" even if the placement wasn't logical.
I also find I have a really hard time with complex math because my brain gets stuck on the simplest bits.. I know the answer, but keep repeating the equation in my brain over and over anyway.
It's funny how common an obsession with the number 3 seems to be among people with OCD. I used to constantly spell words out in my head in repeated sets of 3.
Also, if I've had a long day my brain sort of shuts down at night and I can't make sense of things anymore. hah
I can't really hold a solid conversation if I've already been mentally stimulated all day, it's like my brain gets as tired as my body.
I disagree with saying everyone has it to a degree, nah. I don't think so.
It's also a bit annoying when people say "oh I'm so OCD about that!"