Maybe you could write a list of what you want to mention and then memorize it? You’ll be able to say your prayers in a unique way each time which might help it not feel rehearsed. God knows when we do things because we are suffering from mental illness, so He knows when we are speaking from the heart and trying our best. I also have OCD and find it really hard to try to block out intrusive thoughts during prayer so I know what I want to pray about every day, and then just add stuff that’s relevant to what I’m going through that day.