First off, it's VERY important to be aware that
everyone has weird thoughts------people with ocd and people without any sort of anxiety or mental disorder. This is an
incontrovertible fact.
The difference between people without ocd and those with ocd, is just simply the fact that ocders get "stuck" on their thoughts.
That's all there is to it.
Every quote, unquote "normal" person has weird thoughts about possibly being gay, or gets weird images in their mind of really sick things they would never do in reality. They are just able to naturally dismiss it, or forget about it, or laugh it off.
The ocder on the other hand, gets stuck on those thoughts/images and finds it very hard to switch gears.
So take comfort in the fact that not only are you NOT the only ocder who has these thoughts/fears, but you are also NOT the only person in the world either (including the most 'normal' of people everywhere).
I'm using the word 'normal' for the sake of being able to label, by the way......I definitely don't consider myself or anyone else with any sort of mental affliction as being "abnormal."
We all know 'normal' is only a subjective term anyways....
But I had to generate this little disclaimer to be sure everyone knew what I meant----
And yeah, I have gotten headaches from thinking too much. I chalk that up to just the fact that I've been overthinking and straining my mind.
For me, it's the same sort of headache I would get when I was actually concentrating ALOT on something that held a much better purpose (I hate ocd thought.....such a waste of our time!).
Anyways, a specialist would be able to properly diagnose you, but it sounds like you definitely have ocd tendencies. I'd go see someone to rule out anything else though. Chances are you'll find that you fill a few different slots in their medical diagnosis book (the good ol' DSM manual!

)
Diagnoses are important to get an idea of what areas you need help in, but they can get pretty convoluted, so don't let them get you down or make you feel like you're a complete psychological mess!
Nobody really knows for sure if there is a chemical imbalance in OCD. All of this research into mental disorders is really only in its infancy stage. There are too many things still unknown about OCD and every other affliction.
If a chemical imbalance was really an overshadowing factor in OCD, then the meds I have been on would've helped out alot more than they ever did.....or maybe their definition of chemical imbalance is just directed towards the wrong biological function(s).
So I would offer you the advice to not focus so much on there being some kind of chemical imbalance---it's just too ambiguous at this point.
On the other hand, if there are any OCDers who can honestly say that popping a pill has helped them 90%, then I would be wrong---heh heh.
But I haven't heard of that yet.
Meds can be a useful tool, but they don't seem to alleviate ocd with the same success as, for instance, meds for schizophrenia do.
Also, your list doesn't seem too crazy. It's probably alot tamer than what some 'normal' people have stirring in their brain---

Seriously though, you'll find all sorts of people with ocd who have the same sorts of intrusive thoughts or even worse ones.
But as it has been said: Thoughts are NOT actions. And most ocd people NEVER act out their thoughts. They just torment themselves worrying that they might.