As Eden mentioned, it's all about proportions rather than height when you're small. For example, I have a friend the same height but she has short legs (so standover is her critical issue; she rides a very compact 700c Giant) and I have long legs/short reach (so effective top tube is my crunch number; I ride a custom 650c).

It's very difficult to find xs bikes to try, but keep trying as you will learn what geometry suits you. Or get a professional fit as already suggested (if you're a member of club, they might be able to recommend someone reliable). The geometry of your current bike is a good start if it fits (get the data from the manufacturer's website or see Park Tools on how to measure a frame). Key measures (depending on your proportions) are top tube length (your reach) and standover (which you can measure easily anyway). Once you have a feel for those, you'll be able to assess anything that comes up and shop the main brands' websites for what's likely to fit. Good luck.