I’d agree with your parents that you shouldn’t apply ED to Grinnell. It doesn’t sound like you have visited, and going from NY to Iowa is a culture shock. You might like it, you might hate it, but you should not lock into Grinnell with an ED application.
Make an agreement with your parents that you can apply RD and see what the financial aid is. You will, of course, apply to other schools too and be able to compare the schools and the FA.