I have been diagnosed with OCD and all of the symptoms you guys have written about are classic signs of Obsessive-Compulsive Disorder, from my experience, anyway.
Violent thoughts, sexual thoughts, especially thoughts that repulse you and make you feel sick and disgusting are symptoms of OCD. There is nothing wrong with these thoughts. Having these thoughts does not mean you are going to carry them out. My doctor told me that he felt safer with someone that had OCD and had violent thoughts than a normal person with violent thoughts because the violent thoughts are so repulsive to someone with OCD that they would never act on them.
I know your suffering. The tapping, the checking, the fear that someone will be hurt if you don't do a particular compulsion, the counting. Want to know my numbers? They are: 1,3,5,6,7,9,10,12,15,16, 20-24, and from 30 up. The numbers in between are my worry numbers. If I tap something 8 times, I have to tap it one more time to make it 9. Of course, some numbers are safer than others. To me, 3 and 9 are the safest of all those numbers.
Sorry, I've rambled on a bit.
leigh, don't let your friend tell you what you're going through. Talk to your parents about seeing a doctor and ignore her complaints. Good luck, champ.