How do I build confidence when I'm responsible for big decisions but still afraid?

You fought for the autonomy, and now that you have it, the weight of it can be frightening. Every decision is yours, and somewhere in the back of your mind sits the call you might get wrong. That fear is not a sign you are not ready. It is the natural companion of real responsibility, and the people who feel none of it are the ones to worry about. Confidence is not something you find before you act. It is built by acting carefully, over and over, and watching yourself get it right. You will not feel sure first and then do the work. You do the work with the fear present, make good calls, learn from the close ones, and slowly the fear shrinks as the evidence of your competence grows. Trust the process that is already underway. Meanwhile, use the fear well. Let it keep you careful, let it make you double-check, let it push you to ask a colleague when something is genuinely unclear. Asking is not weakness, it is good medicine. You are not caught between autonomy and fear so much as walking the normal early road of every provider who takes the job seriously. Keep making careful calls. The confidence is coming, one good decision at a time.