Has anybody gotten a titer test to check antibodies without doctor's orders?

My doctor said not to worry about it if I got all my vaccines as a child. But I didn't know how to tell her that I'm a paranoid prepper so I really want to get a titer test just to make sure my antibodies are still up to par.

Has anybody gotten that test without a doctor's orders? I want to do it anyway. I don't see the harm in making sure.