How to determine your size?  
    Start with WAIST size first, then BUST.

For example, your measurements are (27.5 bust), (24 waist) and size chart for the dress is as following.

Size Chart for Dress

    6 8 10   Your Measurements
BUST   24.5 26.5 28.5   27.5
WAIST   23 25 27   24

Take following steps:

1) Start with your WAIST measurement, which is 24, and compare it to WAIST size of 6. Size 6 is too tight so consider Size 8 or 10 for now. 

2) Next, look at your BUST size, which is 27.5, and it's bigger than size 8(26.5), so drop Medium and look at Large.  BUST measurement for Large is 28.5, so it's OK.

If you find an error in measurements, please let us know. It will be appreciated very much. Email to info@TheRoseDress.com