This question gets asked a lot. And there are a variety of answers. What sort of weight is the pony used to carrying? How fit / healthy is the pony? What is the pony's current workload and how experienced are you? Are you a good capable rider and do you have a good position? A learner rider that is nervous or simply hasn't had many lessons won't sit like one that is capable and has a good seat (which would distribute their weight evenly.) How old is the pony? What will you be doing with the pony? You aren't too tall, but I am not sure on the weight because you also have to add into that tack. Sorry for all the questions! I'm sure others will chip in.