Hi Carrie,
Part of the problem is that it IS a formal ball - and that means formal attire; that's just part of ettiquette I'm afraid. Guys have to wear things that choke them and girls have to wear things that go down to their feet.
However; I don't think your outfit has to be so..."frou-frou".
There are many sleek dresses out there today, things that are not so frilly and pouffy.
Try looking around online, and see if there are some dresses that appeal to you at least
some. Here are a couple of links for you to look around at.
Prom Girl 4 Prom As far as jewelry goes; show your mom and grandmom the current trend in Hollywood is the bare neck with just a bracelet. If you pull up pictures of the Oscars - half the women did not wear necklaces or earrings - it was the big fashion talk st the time. Bracelets are the big thing right now.
And you never want to go overboard on perfume and makeup anyway; subtlety is a sign of sophistication, drowning yourself in scent and blue eyeshadow is not.
Also; sleek straight hair is the "in" thing as opposed to ringlet curls. Even tight ponytails to the head (as long as it's not done up on top of your head like in "Grease")
So do a little research on your own; compromise - find some things that you, maybe not love, but at least can live with for one night.
And keep that in mind - it is one night, as opposed to having your mom and grandmother on your back for weeks before and after. (Moms have loooong memories, mine still reminds me of when I snuck out of the house at 16, and I'm 37 now!)