Vertical shins are not for everyone. Having the knees between the forearms is okay. I do that. Vertical shins works for some folks but you might not be some folks. Your first rep looked good. After that you went insane.
Definitely accept the advice above to only perform successful reps and not beat yourself into oblivion.
Also take the above breathing advice seriously.
Stop throwing your head back. You do not pull from the back of your head, you pull from the top of your thoracic spine!!!!!!!!!!!! Change your imagery.
You need a lot of practice setting up correctly and giving it hell. Sometimes, sets for reps changes the subject enough to make it stop resembling powerlifting. Deadlift is both an exercise AND an event. You need to train both.
Have you considered singles training? Forces you to hate the clock, practice the approach, practice setting up, practice breathing, practice grasping, practice pulling like hell, practice GETTING AWAY FROM THE BAR. Needn't be the entirety of your DL training action, but putting something on the bar and pulling 15 - 20 singles in short order trains the event, that is, the single pull.