My Dads 50th Birthday Party - What to wear?

Its my Dad's 50th Birthday Party on Saturday night. Its the first time I'll be seeing a lot of the family since I've lost all the weight, and obviously I want to look as good as possible! Having a right job trying to decide what to wear, why is it that the more you have in your wardrobe the less you seem to have? I've never been one of these people who can work the capsule wardrobe look either! It's just a house party so I don't want to over dress, but still want to look smart, sexy and edgy. This is what I'm considering at the moment -



This is Miss Selfridge Embellished Tee, Dorothy Perkins Black (skin tight) treggings, Miss Selfridge shoes (which I love!), multi chain necklace from warehouse, clip on earrings from warehouse, envelope clutch bag - vintage and for make up I'm thinking nice smoky eyes, nude lips with dark red nails.

I'll probably change my mind, I always do!