I Have Ocd

I always have to wash my hands for a really long time after I take a dump; I'm really coprophobic. I really hate just wiping after wards, so I always have to watch my hands and underneath my fingernails for at least 15 seconds, if not more. I usually just do the soap for 15 minutes or more, and then just wash them with water for a 5 seconds, but I think I'm supposed to do both washing the hands under the water with the soap on for 20 seconds. If I don't hit either 15 or 20 (or in some rare cases, 30) seconds of washing hands with soap, then I have to restart my count. Sometimes I wonder if I even counted the seconds correctly (like, was what I counted as 1 second really a millisecond?, was I counting too fast?, etc.)