I am both a RN and a RD. I keep both licenses currrent. I worked as an RD years ago but choose to work as an RN now. I don't think I will ever go back to being only an RD. In nursing there are many. many more job possiblities, but the main reason I choose nursing as my career is because I get more involved in the whole picture of a person's health, not just on what they eat. For example, as an RN working with a diabetic patient, I can get involved in what's happening with their medications, with symptoms affecting their eyes, kidneys, stomach, feet, etc. and not just on their diet. I can draw blood and explain what all the blood tests mean, take vital signs, etc. and not just talk about menus and carbohydrates. I do use my nutrition background a lot but it is so great to be able to do much more than that.
Do an interesting google search with "RD RN". You will see the resumes and job positions of others who have both licenses. You will see that some have chosen to emphasize nursing in their career and others dietetics. Everyone has different ideas on what's an interesting career. Good luck to you!