Although I don't sew custom-made dresses, I need to know your approximate body measurements to use the appropriate pattern. This way, I can also alter the dress if necessary.
You will need a dressmaker's tape measure. They are sold at haberdashery or bazaars.

Take your measurements in underwear (with the bra you normally wear with this type of dress):
Bust (largest area):
Waist (narrowest area):
Hips/buttocks (widest area):
Distance from shoulder to bust (point A to point B in the image):
Dress length from shoulder:
Remember not to pull the tape measure too tight.
Look at the images. Don't hesitate to contact me if you have any problems taking measurements. I will help you.