I'm 5'7 like you, 140 lbs, and i'm still growing. I haven't hit my growthspurt yet so I got the large, hoping that over this summer i will grow a few inches. For you i think either a small or medium. Depending on how long your arms are i would go with the small,as long as you stopped growing*. And its also based on personal preference , if you think it fits then it fits. Hope this helps!!