Well, you are not going to find a nursing position that has a similar role to a physician at the undergraduate level regardless of the specialty you pick. However, if you wish to pursue graduate education; you can work towards your Masters of Science in Nursing and specialize as a Nurse practitioner. In your role as a nurse practitioner, depending upon your state--you will have prescriptive authority as well as the ability to admit and discharge patients and to create orders for those patients.
If autonomy is what you are seeking, then you might look into Family Nurse Practitioner(FNP). This board certification allows you to open your own clinic; in accordance to the regulations set forth by your particular state's board of nursing.