No, of course you don't need to wear anything you don't want to!!!
In terms of style,, you could go with something a bit different and try to style waves into your hair or if you're not going to do anything with your hair or put anything in it, maybe you could wear some fantastic earrings for bling.
If you're open to trying different accessories (other than tiaras), you could try wearing a thin headband (almost invisible) with something fun for the side on it like flowers, crystals or feathers
Or an actual clip/fascinator headpieces, like the following:
They'd give some nice colour too!
I think this one is gorgeous - by LoBoheme (Etsy)
Even if you're not someone who likes to stand out, don't sell yourself short - be sure that you will feel special and glamorous enough on your WD!