i have a 50 and i'm 5'4. my legs are longer than my arms and the 50 is great. i just jack the seatpost higher and my ride a stem about 100/110 mm with a rise otherwise i can't reach the drops. my friend is 5/8 with a 33 inseam and she rides a 53 and she says it's to small for her. sooooo ur best best is to get the 53. or find someone near u that has an iro in a 53. i know that probably doesn't help.
p.s i'm a female