Hi ~ I have "some" OCD and can relate to what you're talking about. I've worked hard to control some of my issues, but i don't always have luck.
As for your "A" problem, "future worries for no reason" ~~ This is what helped me. I figure that we aren't even PROMISED tomorrow - all we have is today. By worrying and obsessing about the future, we're just ruining today and boy have I ruined alot of "todays." So I had to focus on NOT worrying - if that makes any sense. LOL If I began to obsess again about tomorrow or the future, then I'd switch what I was thinking about to something nice -- like a trip i had taken, or a pretty song that I liked. Pretty soon I had stopped consciously worrying about the future. At least it worked for me.
The repetitive things is a little harder for me to quit --- such as my verticle blinds -- if they aren't hanging "just so" I get all out of whack. I have to go straighten them.
I'm double checking myself 2-3 times - which isn't too bad. it used to be more than that. LOL I'm trying to "lighten up" on the repetitive things but it's going to take more time.
So you're not alone. I guess for me it's just going to take more work -- but I have made some strides in the obsessing about the future so I'm happy with that. Best of luck to you and God bless! Hugs, Lee