There are two things to try when casting across your body: rotate the rod in your hand so the reel doesn't hang below the rod, but to the side when you are completing the casting stroke and try holding the running line in your top hand, rather than your bottom hand. I've never learned to cast with my left hand up. Those who did are grateful. I hope an ambidextrous member can add to your post. https://www.youtube.com/watch?v=b7XJKm92Fs8
This clip might help you with the top hand during the cast...Wait for it.
Thanks and thanks for the vid- very helpful. I think at this point, I'll keep working on both right and left hand up casting and see if it keeps progressing. Hard to even find a place to practice when the rivers are so high. Of course this is the kind of winter we'd have when I get interested in steelhead fishing !