Fit is obviously the most important consideration in a bike. The thing is that many brands have huge sizing differences. My suggestion would be to go to your local bike shop and take a look at the different popular brands and components. See if they can do some quick sizing and give you some suggestions. There's no shame in telling them you might need to look used. Just let them know that they will get your business for repairs and other necessities. They might even know of a decent bike for sale. That will give you an idea of what you are looking at when you jump into the used market.
I am 5'7 1/2" and ride a 54 Specialized Roubaix pro with a shortened stem. I am long in the torso and measured 53.3. I felt better on a 54 than 52 with longer stem. The cool thing with your size you don't need to limit yourself to women's specific bikes. Let us know what you find. The folks on this site are the best for bike advise.