I once committed to a chiropractor for a lengthy series of treatments that I could not get anywhere else. It was worth it.
But what do you get for that? How sick are you? Is nutritionist certified in your needs? It’s nice to have someone connected with your doctors office, but will you need that length of time ( I presume it’s many appointments) could you have an appointment or two to see how you like that person? Then commit.
It took me a while to get into a dieticians office, and by the time I did, like you, I had done all of the research I could get my hands on and she had nothing new to add. She agreed that the one visit was probably enough.
Is there a dietitian near you that charges by the visit? You could at least get that information to help you decide if you want to make that large commitment.
Again, maybe you need the whole of the services they offer; but I would at least ask around a bit…