I am 5'5 and my legs aren't particularly long for a woman, and I ride a 53. It makes sense to me that you might need a bigger bike.

You also might want to look at a bike with less upright geometry, one with a level top tube. That can also change the fit ... my new compact geometry road bike is a 53, my older traditional geometry road bike is a 51. They ride a little differently but they are both comfortable.