How can you be sure if you have ocd, just wondering?

Go to a psychologist: Diagnosing OCD is relatively straightforward, but you need to go to someone trained to ask the right questions. There are rare medical conditions that mimic OCD symptomotology, but generally there is a core list of symptoms that you can find on the internet, to start, although never rely on "doctor internet" for a diagnosis. Psychology Today is a good place, but also see: www.nimh.org