Organising of a girls weekend to Melbourne

So my girlfriend is organising a Trip to Melbourne for her 50th Birthday, to start with it was going to be a midweek Melbourne cup few days but have now decided to go the weekend following the "Big Race" less people we hope, still heading to the races.
Accommodation Booked staying in Flinders Lane nice and close to food and alcohol yay! so she sends me a message to tell me that she has booked the flights we have carryon luggage only OMG!!! I can fit my makeup and shoes in carryon and trust me I am not a girly girl who wears lots of makeup or owns a bizzilon pairs of shoes it's just how can you pack for 3 days in carryon to Melbourne! Melbourne weather is so unpredictable as is Sydney weather these days:
I am sure I will work it out!

Here are some pictures of my last trip!

                                                        My Last Trip to Melbourne