There's a screening quiz right here:

http://psychcentral.com/ocdquiz.htm

I think obsessive thinking is a kind of "compulsion" (or you wouldn't do it obsessively) is why they're together. Thinking is an act and can have compulsive elements in and of itself. "I keep getting these disturbing images in my head and the more I want to stop thinking about them, the more I do." -- that's a very good definition of a compulsion.

I'm glad you're seeing a counselor and getting an evaluation. No reason at all you can't help yourself. Good luck! We can only think one thing at a time (there's really no such thing as "multi" tasking, it's actually sequential tasking, one thing at a time in a row :-) so you can keep taking your thoughts off obsessive ones to other ones you choose. It's hard work but eventually the obsessing should "give up" and relax itself so it's not so hard. One thing that helps me is remembering what "jingle" experts say about how to get rid of a repetitive song/music in your head; you either have to do the whole song to completion, giving "closure" or replace it with a different one (which, hopefully, won't get stuck too).