One of my best friends has that problem too. Lots of nightmares and hard to remember anything. I wish I knew how to work with that. Waking intent can have a lot of influence on dreams, but if the subconscious has strong reasons for blocking recall, a sneakier approach may be necessary. I wonder what would happen if you got up in the morning and made up a nightmare to write down. Just took that bad nightmare feeling and wrote a story from it. It all comes from the same place anyway, so maybe that's a way to gently break through the block. Kind of saying, "Fine, if you won't let me remember my dreams, I'll make up my own. Nyah nyah nyah."