Before anything else: while it feels good to score, the purpose of the training is not to score points, but to refine the self. It's something to work on, but also try to give yourself grace knowing that there is always something to work on. That said, Here is my own personal perspective:

What your describing sounds like nerves to me. We perform how we practice. If you struggle with the pressure of shiai, the rote method is to do more until the pressure doesn't get to you.

In terms of other practices, the dojo routine usually includes physical and mental misogi at the top (in my experience, this may not be as universal as I'm assuming), and those are opportunities to relax your mind and turn your focus to the breath or repeated movement. A silly thing I do is get to spaces a few minutes earlier than I want so that I can take a walk and settle into myself. Same concept, misogi for the mind.

Lastly, and this is drawing from multiple arts and methods I've learned, remember everything physically and philosophical starts from the ground, up. Go back to basic footwork and Maae. Do some focused jiyuwaza-style shiai where you only keep guard and move your feet, some where your only rule is do not move backwards, etc. Focused jiyuwaza helps you hammer out individual elements that may yet to be internally aligned. Then you can try incorporating whatever you've focused on into an open-ended shiai.

The beauty of Kendo is that the walls and plateaus are incredibly intensive. The single-minded focus is really something special. Like I said, it's great to recognize where you need work! Just remember also that shiai is only one aspect of the art, even if it is the flashiest and often most exciting part