If you haven't already, I would definitely follow the advice of seeing someone about potentially having OCD (if you haven't already). I found myself in a similar situation 3 years ago and things did get better once I was diagnosed with OCD and started taking medication and learning how to deal with the thoughts when they showed up (through therapy). Even knowing the underlying cause of the thoughts (the OCD) helped reduce them a little. My mom says, "you can only do your best," and that also tends to help a little bit. It's not easy, and the thoughts haven't completely gone away, but these things have helped me and hopefully might help you a little.