How do I handle difficult vendors and crunch times?

You can coordinate the normal flow. What buries you are the difficult vendors and the crunch times, when everything lands at once and every problem needs you now. That is the hardest part of the job, so struggling there is not a sign you are bad at it. In a crunch you cannot do everything, so the skill becomes choosing. What truly must happen today, and what only feels urgent? Handle the few things that will actually sink the project if they slip, and let the rest wait or go to someone else. Trying to hold all of it at once is exactly what buries you. With the difficult vendors, stop absorbing the chaos and start setting the terms. Be clear about what you need and by when, in writing, and hold the line calmly. You cannot make a hard vendor easy, but you can stop letting their disorder become yours. Sort what matters, set clear expectations, and carry less by carrying only what is truly yours.