OCD is when you obsess over something. When someone begins to obsess or become neurotic over something for a long period of time this can produce a lot of anxiety.
You need to be on the look out for physical behaviors that are done for the purpose of easing the anxiety produced by the obsessions. For example, If you have OCD you may have the recurring thought of disaster befalling a loved one. You may feel that you can protect your loved one by touching your closet door four times every time this thought comes up. This behavior is a compulsion and is a classic symptom of OCD.
You also need to look at the length of time you spend on thes compulsions every day. If you spend and hour or more of your time performing these compulsions on any given day, this is a strong indicator of OCD.