I have Pure-O and I’ve been praying everything like mad. The Rosary, the Divine Mercy Chaplet, the Servite Rosary, the Novena to Our Lady of knots. The thing is, I think it’s working. After hiding my suffering for years I got super sick and had to be hospitalized. That is when my family found out and I was actually able to get help. Help sometimes comes to us in strange ways, but it comes. Pray hard and strong. That being said, for intrusive thoughts I like St. Catherine of Siena. Her spiritual temptations were almost identical to OCD intrusive thoughts. St. Alphonsus Ligouri had OCD( his only manifested as scruples though). St. Therese had intrusive thoughts as did St. Faustina. Regardless of weather they had OCD or not, they understand the struggle. I’m sure any one of them is happy to help us.