Glamorous dress needed for a short fat bird - Help!

[ChristmasJumperWearer]

I've been invited to what promises to be a very glamorous party this Christmas, but don't have a clue what to wear!

I've put on a bit of weight that I haven't been able to shift, so am 5ft3 with small-ish boobs, a bit of a tummy, big bum (all about that bass, etc). Late 30's.

Pale skin. Black is too harsh for me, I suit colours such as navy blue, purple, emerald green I.e. jewel brights, not bright red/coral though. Others at the party will be fashion-followers. I'm not, but it would be great to find something that ticks that box too.

Budget is flexible - maybe a few hundred pounds?

Help me, please!