I am 5'5" on a good day. I have a Specialized Dolce Sport in a 54 cm and it fits great. However, my two Treks, a 2.1 WSD and a Madone 5.2 WSD, fitted by different shops, both are 52 cm. So, as stated above, there are differences in brands. Go with what feels/fits best and makes you smile and want to ride more.

P2